Traffic Analysis Zones's (TAZ) Population Data
Metadata also available as
Metadata:
- Identification_Information:
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- Citation:
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- Citation_Information:
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- Originator: Loudoun County, VA, Department of Planning, Demographer
- Publication_Date: 20140326
- Title: Traffic Analysis Zones's (TAZ) Population Data
- Geospatial_Data_Presentation_Form: tabular digital data
- Other_Citation_Details:
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Loudoun County's Traffic Analysis Zones (TAZ) were delineated by Loudoun County Government in cooperation with the Metropolitan Washington Council of Governments (MWCOG). The TAZ layer has been modified from the MWCOG TAZ GIS layer. When the MWCOG GIS layer is overlaid with Loudoun County Government's detailed GIS layers it can be determined that the MWCOG TAZ boundaries in some cases are slightly off from the actual location of the physical features, natural features, and governmental units such as town boundaries that they are designated to follow. The Loudoun TAZ layer was generated by Loudoun County so that the TAZ boundaries would overlay with the features in Loudoun County's GIS data sets that the boundaries are designated to follow. The forecasts for the TAZs are updated by Loudoun County generally once every year to account for changes in market conditions, rezonings, and comprehensive plan amendments. The TAZ boundaries remain unchanged for a period of about ten to fifteen years.
- Description:
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- Abstract:
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The population data represents Loudoun County's Round 8.3 Metropolitan Washington Council of Government's Cooperative Forecasts as of March 7, 2014. Data for 2010 are derived from the 2010 Decennial Census and provide a basis for the forecasts. The 2015 to 2040 data are forecasts of the total population expected in Loudoun County from 2015 through 2040 in five-year increments by Traffic Analysis Zones (TAZ). Forecasts for the TAZs are produced by Loudoun County by accounting for regional and local market trends, zoning, planned land use, and the long-range supply of land.
- Purpose:
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The current TAZ boundaries are used for statistical data tabulation purposes, including the current MWCOG cooperative forecasting rounds and future forecasting rounds through approximately 2020. TAZ forecasts are used for demographic analyses of Loudoun County, as well as for Loudoun County and Washington, D.C. regional planning purposes. A detailed picture of population, housing, and employment, within a TAZ is gained from the TAZ forecasts. TAZ forecasts are also used extensively for transportation modeling and transportation planning.
- Supplemental_Information:
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Data are stored in the corporate ArcSDE Geodatabase as a polygon feature class. The coordinate system is Virginia State Plane (North), Zone 4501, datum NAD83 HARN (vertical datum, if applicable, NAVD88), US Survey foot units.
- Status:
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- Progress: Complete
- Maintenance_and_Update_Frequency: Irregular
- Keywords:
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- Theme:
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- Theme_Keyword_Thesaurus: None: Employee generated
- Theme_Keyword: population
- Theme_Keyword: boundary
- Theme_Keyword: boundaries
- Theme_Keyword: demographic
- Theme_Keyword: TAZ
- Theme_Keyword: traffic
- Theme_Keyword: COG
- Theme_Keyword: housing units
- Theme_Keyword: household
- Theme_Keyword: region
- Theme_Keyword: forecast
- Theme:
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- Theme_Keyword_Thesaurus: ISO 19115 Topic Categories
- Theme_Keyword: society
- Theme_Keyword: boundaries
- Place:
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- Place_Keyword_Thesaurus: None: Employee generated
- Place_Keyword: Washington
- Place_Keyword: Virginia
- Place_Keyword: D.C.
- Place_Keyword: 51107
- Place_Keyword: DC
- Place_Keyword: County
- Place_Keyword: Loudoun
- Access_Constraints: None
- Use_Constraints:
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These data were generated for use by Loudoun County and are available to the public. These data are intended for use at 1:2400 scale or smaller. Acknowledgement of Loudoun County would be appreciated in products derived from this data.
- Point_of_Contact:
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- Contact_Information:
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- Contact_Organization_Primary:
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- Contact_Organization: Loudoun County, VA, Department of Planning
- Contact_Position: Demographer
- Contact_Address:
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- Address_Type: mailing and physical
- Address: 1 Harrison St. SE
- Address: MS 62
- City: Leesburg
- State_or_Province: VA
- Postal_Code: 20175
- Country: US
- Contact_Voice_Telephone: (703) 777-0246
- Contact_Facsimile_Telephone: (703) 777-0441
- Contact_Electronic_Mail_Address: dop_loudoun.gov
- Hours_of_Service: 8:30-5:00 EST, M-F
- Native_Data_Set_Environment:
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Microsoft Windows Server 2008 Version 6.0 (Build 6002) Service Pack 2; ESRI ArcGIS 10.0.5.4400
- Data_Quality_Information:
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- Attribute_Accuracy:
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- Attribute_Accuracy_Report:
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Retention of attribute accuracy throughout the personal geodatabase or shapefile to ArcSDE geodatabase feature class coversion process was ensured by a manual or automatic QA/QC programmatic check. To meet satisfactory QA/QC requirements the input coverage and output feature class must have, on a record by record basis, identical attribution when comparing all concatenated fields to all the user-defined attribution.
- Logical_Consistency_Report: Topologically clean
- Completeness_Report:
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Features may have been eliminated or generalized due to scale and intended use. To assist Loudoun County, Virginia in the maintenance of the data, please provide any information concerning discovered errors, omissions, or other discrepancies found in the data.
- Positional_Accuracy:
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- Horizontal_Positional_Accuracy:
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- Horizontal_Positional_Accuracy_Report:
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Retention of coordinate accuracy throughout the personal geodatabase or shapefile to ArcSDE geodatabase feature class conversion process was ensured by a manual or automatic QA/QC programmatic check. To meet satisfactory QA/QC requirements the input coverage and output feature class must have the same record total, and on a record by record basis, area, perimeter, and length differential of less than +/- 0.5%.
- Lineage:
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- Source_Information:
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- Source_Citation:
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- Citation_Information:
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- Originator: Loudoun County Department of Management and Financial Services
- Title: Loudoun County Department of Planning
- Geospatial_Data_Presentation_Form: spreadsheet
- Type_of_Source_Media: hardcopy
- Source_Citation_Abbreviation: Loudoun County Department of Planning
- Source_Contribution:
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Loudoun County Department of Planning is the source for population, housing units, households, and employment for TAZs.
- Source_Information:
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- Type_of_Source_Media: onLine
- Source_Contribution:
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The 2010 Census SF1 block data were the basis for deriving the demographic data.
- Source_Information:
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- Type_of_Source_Media: None
- Source_Time_Period_of_Content:
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- Time_Period_Information:
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- Single_Date/Time:
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- Calendar_Date: 20110101
- Source_Currentness_Reference: Unknown
- Source_Contribution:
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Loudoun County Government GIS digitized block lines for aligning TAZ data with Loudoun County GIS data
- Source_Information:
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- Type_of_Source_Media: None
- Source_Time_Period_of_Content:
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- Time_Period_Information:
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- Single_Date/Time:
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- Calendar_Date: 20100101
- Source_Currentness_Reference: Unknown
- Source_Contribution:
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TIGER/Line files provided the foundation upon which census blocks were drawn. The 2010 Census blocks were the basis for devising the TAZ boundaries.
- Process_Step:
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- Process_Description:
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The following is a description of the process used to derive the 2010 population, household, and housing unit totals. The TAZ shapefile from the Metropolitan Washington Council of Governments was overlaid the with Loudoun County Government's detailed GIS layers to determine the actual location of the physical features, natural features, and governmental units such as town boundaries that the TAZs are designated to follow. Census blocks are designated to follow these types of features as well. Census block shapefiles were downloaded from the U.S. Census Bureau. Overlaid the Census Bureau block shapefile with Loudoun County Government's detailed GIS layers to determine the actual location of the physical features, natural features, and governmental units such as town boundaries that the census blocks are designated to follow. Digitized block lines using Loudoun County Government's detailed GIS layers. TAZ boundaries that do not follow block boundaries were identified. The identified boundaries were digitized using Loudoun County Government's detailed GIS layers, and in doing so, census blocks were split into parts. Created the TAZ layer by assigning the TAZ number to each census block or census block split area and then spatially dissolving the census block with splits layer. The 2010 population, household, and housing unit totals were derived by summing U.S. Census Bureau 2010 Census block and census block split area totals. For split census blocks, the percentage of a blocks housing units that existed for the 2010 Census in the split area was determined using a combination of building permit, occupancy permit, and assessment data. This calculated percentage for a census block's split area was then multiplied by the population, household, and housing unit totals of the census block to derive the estimated population, household, and housing unit totals for the block split area.
- Process_Contact:
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- Contact_Information:
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- Contact_Organization_Primary:
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- Contact_Organization: Loudoun County Department of Planning
- Contact_Position: Demographer
- Process_Step:
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- Process_Description:
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The following is a description of the process used to derive the 2015 to 2040 population, household, housing unit forecasts. First, the forecasting of new housing units by unit type for TAZs is performed using issued building permits, zoning, planned land use, local market trends, the long-range supply of land, and guidance from the Loudoun County Fiscal Impact Committee, a Loudoun County Board appointed committee. The forecasted new households is calculated by multiplying the forecasted housing unit occupancy rate of a unit type by the number of new housing units of a unit type and summing the results of each unit type calculation. The forecasted new population is calculated by multiplying the number of new housing units of a unit type by the forecasted housing unit occupancy rate of a unit type and the household size of a unit type and then summing the results of each unit type calculation. The total population, households, and housing units for 2015 to 2040 are forecasted by using the 2010 Decennial Census total housing units. households, and population by TAZ as the basis. The total new population, new households, and new housing units is added to the previous five-year period's total overall number.
- Process_Contact:
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- Contact_Information:
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- Contact_Organization_Primary:
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- Contact_Organization: Loudoun County Department of Planning
- Contact_Position: Demographer
- Spatial_Data_Organization_Information:
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- Indirect_Spatial_Reference: Loudoun County
- Point_and_Vector_Object_Information:
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- SDTS_Terms_Description:
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- SDTS_Point_and_Vector_Object_Type: GT-polygon composed of chains
- Point_and_Vector_Object_Count: 282
- Entity_and_Attribute_Information:
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- Detailed_Description:
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- Entity_Type:
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- Entity_Type_Label: GISDBB.GISBROW.TAZ_POPULATION
- Attribute:
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- Attribute_Label: HH_POP_2040
- Attribute_Definition: Estimated Household Population in 2040
- Attribute_Definition_Source: Department of Planning
- Attribute_Domain_Values:
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- Unrepresentable_Domain: user generated text
- Attribute:
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- Attribute_Label: HH_POP_2030
- Attribute_Definition: Estimated Household Population in 2030
- Attribute_Definition_Source: Department of Planning
- Attribute_Domain_Values:
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- Unrepresentable_Domain: user generated text
- Attribute:
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- Attribute_Label: HH_POP_2035
- Attribute_Definition: Estimated Household Population in 2035
- Attribute_Definition_Source: Department of Planning
- Attribute_Domain_Values:
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- Unrepresentable_Domain: user generated text
- Attribute:
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- Attribute_Label: HH_POP_2025
- Attribute_Definition: Estimated Household Population in 2025
- Attribute_Definition_Source: Department of Planning
- Attribute_Domain_Values:
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- Unrepresentable_Domain: user generated text
- Attribute:
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- Attribute_Label: HH_POP_2010
- Attribute_Definition: Estimated Household Population in 2010
- Attribute_Definition_Source: Department of Planning
- Attribute_Domain_Values:
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- Unrepresentable_Domain: user generated text
- Attribute:
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- Attribute_Label: GROUP_QTR_POP_2035
- Attribute_Definition:
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Estimated Group Quarters (e.g. nursing home, college dormitory, prison) Population in 2035
- Attribute_Definition_Source: Department of Planning
- Attribute_Domain_Values:
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- Unrepresentable_Domain: user generated text
- Attribute:
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- Attribute_Label: GROUP_QTR_POP_2040
- Attribute_Definition:
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Estimated Group Quarters (e.g. nursing home, college dormitory, prison) Population in 2040
- Attribute_Definition_Source: Department of Planning
- Attribute_Domain_Values:
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- Unrepresentable_Domain: user generated text
- Attribute:
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- Attribute_Label: GROUP_QTR_POP_2025
- Attribute_Definition:
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Estimated Group Quarters (e.g. nursing home, college dormitory, prison) Population in 2025
- Attribute_Definition_Source: Department of Planning
- Attribute_Domain_Values:
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- Unrepresentable_Domain: user generated text
- Attribute:
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- Attribute_Label: GROUP_QTR_POP_2030
- Attribute_Definition:
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Estimated Group Quarters (e.g. nursing home, college dormitory, prison) Population in 2030
- Attribute_Definition_Source: Department of Planning
- Attribute_Domain_Values:
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- Unrepresentable_Domain: user generated text
- Attribute:
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- Attribute_Label: GROUP_QTR_POP_2010
- Attribute_Definition:
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Estimated Group Quarters (e.g. nursing home, college dormitory, prison) Population in 2010
- Attribute_Definition_Source: Department of Planning
- Attribute_Domain_Values:
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- Unrepresentable_Domain: user generated text
- Attribute:
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- Attribute_Label: POP_2035
- Attribute_Definition: Estimated Total Population in 2035
- Attribute_Definition_Source: Department of Planning
- Attribute_Domain_Values:
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- Unrepresentable_Domain: user generated text
- Attribute:
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- Attribute_Label: POP_2030
- Attribute_Definition: Estimated Total Population in 2030
- Attribute_Definition_Source: Department of Planning
- Attribute_Domain_Values:
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- Unrepresentable_Domain: user generated text
- Attribute:
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- Attribute_Label: POP_2015
- Attribute_Definition: Estimated Total Population in 2015
- Attribute_Definition_Source: Department of Planning
- Attribute_Domain_Values:
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- Unrepresentable_Domain: user generated text
- Attribute:
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- Attribute_Label: POP_2020
- Attribute_Definition: Estimated Total Population in 2020
- Attribute_Definition_Source: Department of Planning
- Attribute_Domain_Values:
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- Unrepresentable_Domain: user generated text
- Attribute:
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- Attribute_Label: HH_POP_2020
- Attribute_Definition: Estimated Household Population in 2020
- Attribute_Definition_Source: Department of Planning
- Attribute_Domain_Values:
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- Unrepresentable_Domain: user generated text
- Attribute:
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- Attribute_Label: POP_2025
- Attribute_Definition: Estimated Total Population in 2025
- Attribute_Definition_Source: Department of Planning
- Attribute_Domain_Values:
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- Unrepresentable_Domain: user generated text
- Attribute:
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- Attribute_Label: TAZ
- Attribute_Definition: Unique identifying number for each TAZ
- Attribute_Definition_Source: Department of Planning
- Attribute_Domain_Values:
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- Unrepresentable_Domain: user generated text
- Attribute:
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- Attribute_Label: OBJECTID
- Attribute_Definition: Internal feature number.
- Attribute_Definition_Source: ESRI
- Attribute_Domain_Values:
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- Unrepresentable_Domain:
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Sequential unique whole numbers that are automatically generated.
- Attribute:
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- Attribute_Label: POP_2010
- Attribute_Definition: Estimated Total Population in 2010
- Attribute_Definition_Source: Department of Planning
- Attribute_Domain_Values:
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- Unrepresentable_Domain: user generated text
- Attribute:
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- Attribute_Label: POP_2040
- Attribute_Definition: Estimated Total Population in 2040
- Attribute_Definition_Source: Department of Planning
- Attribute_Domain_Values:
-
- Unrepresentable_Domain: user generated text
- Attribute:
-
- Attribute_Label: GROUP_QTR_POP_2020
- Attribute_Definition:
-
Estimated Group Quarters (e.g. nursing home, college dormitory, prison) Population in 2020
- Attribute_Definition_Source: Department of Planning
- Attribute_Domain_Values:
-
- Unrepresentable_Domain: user generated text
- Attribute:
-
- Attribute_Label: HH_POP_2015
- Attribute_Definition: Estimated Household Population in 2015
- Attribute_Definition_Source: Department of Planning
- Attribute_Domain_Values:
-
- Unrepresentable_Domain: user generated text
- Attribute:
-
- Attribute_Label: GROUP_QTR_POP_2015
- Attribute_Definition:
-
Estimated Group Quarters (e.g. nursing home, college dormitory, prison) Population in 2015
- Attribute_Definition_Source: Department of Planning
- Attribute_Domain_Values:
-
- Unrepresentable_Domain: user generated text
- Distribution_Information:
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- Distributor:
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- Contact_Information:
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- Contact_Organization_Primary:
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- Contact_Organization: Loudoun County, VA OMAGI
- Contact_Position: Public Information Counter
- Contact_Address:
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- Address_Type: mailing and physical
- Address: MS 65
- Address: 1 Harrison Street S.E., 2nd floor
- City: Leesburg
- State_or_Province: VA
- Postal_Code: 20175
- Country: US
- Contact_Voice_Telephone: (703)771-5778
- Contact_Facsimile_Telephone: (703)771-5075
- Contact_Electronic_Mail_Address: mapping@loudoun.gov
- Hours_of_Service: 8:00-4:30 EST, M-F
- Distribution_Liability: See access and use constraints information.
- Standard_Order_Process:
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- Digital_Form:
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- Digital_Transfer_Information:
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- Format_Name: DXF
- Format_Specification: AutoCad Digital Exchange File
- Digital_Transfer_Option:
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- Offline_Option:
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- Offline_Media: dvd
- Fees:
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Loudoun County distributes spatial data in ArcGIS database or shapefile & DXF format for the cost of reproduction. Countywide spatial datasets may be purchased for $22 per DVD for up to 4.5 GB of data. There is a $100 surcharge to purchase countywide topography, and a $3 charge if the item is to be mailed. If the customer wants the data in DXF format and/or would like OMAGI to custom select specific geographic areas of the County, there is an additional $7 per 15 minute increment labor charge. Select aerial imagery is also available.
- Ordering_Instructions:
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Size limit: 4.5 GB. Visit our website at: <http://www.loudoun.gov/omagi>, click on "Loudoun County Mapping Documents & Order Forms." The "Forms" directory will lead you to custom & standard (countywide) data order forms. Hardcopy maps may also be available; please contact the Mapping Office Public Information Counter for more information regarding all data requests.
- Metadata_Reference_Information:
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- Metadata_Date: 20140328
- Metadata_Contact:
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- Contact_Information:
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- Contact_Organization_Primary:
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- Contact_Organization:
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Loudoun County, VA, Office of Mapping & Geographic Information (OMAGI)
- Contact_Position: Metadata Specialist
- Contact_Address:
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- Address_Type: mailing and physical
- Address: MS 65
- Address: 1 Harrison Street SE, 2nd Floor
- City: Leesburg
- State_or_Province: VA
- Postal_Code: 20175
- Country: US
- Contact_Voice_Telephone: (703)771-5778
- Contact_Facsimile_Telephone: (703)771-5075
- Contact_Electronic_Mail_Address: mapping@loudoun.gov
- Hours_of_Service: 8:00-4:30 EST, M-F
- Metadata_Standard_Name: FGDC Content Standard for Digital Geospatial Metadata
- Metadata_Standard_Version: FGDC-STD-001-1998
- Metadata_Time_Convention: local time
- Metadata_Use_Constraints:
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This metadata reflects the source Geodatabase format and specific elements may not apply if your data is exported to SHP or DXF products. User must be aware that changes to data schema occur during data export that may not be reflected in this metadata, which represents Loudoun County's corporate geodatabase. Acknowledgement of Loudoun County would be appreciated in the use of this metadata.
Generated by mp version 2.9.6 on Fri Mar 28 12:23:19 2014