Data Sources of OnTheMap

The employment data used in this application are derived from Unemployment Insurance Wage Records reported by employers and maintained by each state for the purpose of administering its unemployment insurance system. The states assign employer locations, while workers' residence locations are assigned by the Census Bureau using data from multiple federal agencies. Age, earnings, and industry profiles are compiled by the Census Bureau from a state's records and are supplemented with other Census Bureau source data. Final compilations and confidentiality protection are performed by the Census Bureau.

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Confidentiality Protection

The Census Bureau and its state partners are committed to protecting the confidentiality and integrity of the underlying workforce and employment data files. Statistical techniques are employed by the Census Bureau to ensure that actual statistics are not shown if the numbers in a cell are small. Rather, the mapping displays and tabular reports show synthetic data that are statistically analogous to actual worker counts and locations but not exact.

Technically, the method used to protect the residential address information for each workplace address is called "synthetic data," which involves modeling the underlying data in a manner that protects confidentiality, then making random draws from that model. The method used to protect the workplace information is to combine the confidential data with noise in a manner that ensures that the published data, while not exact, become increasingly more accurate as the number of businesses in a workplace area gets large. No business's actual data are used for any workplace reports. The employment data for private employers are controlled to state-level totals provided by the Bureau of Labor Statistics.

Only Census Bureau employees or individuals who have Special Sworn Status are permitted to work with the underlying confidential data. Everyone who has access to U.S. Title 13 data must have an official security clearance based on a background check, including fingerprinting and face-to-face interviews of selected references, conducted by the Office of Personnel Management. The Census Bureau and state data custodians closely review all projects before release to avoid disclosure of confidential information.

The underlying confidential data used to create OnTheMap Version 3 were protected using synthetic data methods that offer formal privacy guarantees. The peer-reviewed paper describing these methods is available from the International Conference on Data Engineering as:

Machanavajjhala, Ashwin, Daniel Kifer, John Abowd, Johannes Gehrke, and Lars Vilhuber, "Privacy: Theory Meets Practice On the Map," International Conference on Data Engineering (ICDE) 2008, pp. 277-286.

A preprint version can be downloaded here [PDF, 204KB].
How Synthetic Data Work to Protect Confidentiality [PDF, 56KB]
Diagram on OnTheMap Synthetic Data Modeling [PDF, 96KB]

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Geographic Data in OnTheMap

The base map and the majority of geography displayed in OnTheMap use the U.S. Census Bureau's public-use TIGER/Line geography product. Version 4 of OnTheMap makes use of the 2008 TIGER/Line Shapefiles. Further information about the TIGER/Line data, including downloadable shapefiles, can be found at http://www.census.gov/geo/www/tiger/ . Information about specific layers in OnTheMap can be found on the Geographic Sources page.

OnTheMap uses the "USA Contiguous Albers Equal Area Conic" projection for the 48 contiguous states, the District of Columbia, Puerto Rico, and the U.S. Virgin Islands. The "Alaska Albers Equal Area Conic" projection is used for Alaska. And the "Hawaii Albers Equal Area Conic" projection is used for Hawaii.

OnTheMap Version 4 allows the import of shapefiles. Users may either provide a projection file (.prj) or specify an EPSG code. More information on EPSG codes and their specifications can be found at http://www.epsg-registry.org/ .

Several layers use geographic data that was not provided by the TIGER/Line shapfiles. The U.S. Department of Labor Employment and Training Administration (ETA) provides the definitions of workforce and economic development resources, such as the definitions of Workforce Innovation in Regional Economic Development (WIRED) Regions. LED collects the definitions of the Workforce Investment Board Areas from the partner states. Further information about the geographic layers used in OnTheMap can be found on the Geographic Sources page.

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Download the OnTheMap Data

Raw OnTheMap data files can be downloaded from two sources, an FTP download from the VirtualRDC (VRDC) system hosted by Cornell University and an HTTP download directly from the U.S. Census Bureau.

• To gain access to the OnTheMap data on the VRDC system, go to http://lehd.did.census.gov/led/datatools/vrdc.html and follow the instructions provided there.
• To access the HTTP download of OnTheMap go to http://lehd.did.census.gov/led/onthemap/.

In both locations, the files are organized similarly - by state and by file type. Three sets of files are provided: Origin-Destination (OD) data, Residence Area Characteristics (RAC) data, and Workplace Area Characteristics (WAC) data. Currently, data files are provided as Comma-Separated Variable (CSV) files that have been zipped to minimize storage.

For more detailed information on filename organization and structure, please read the OnTheMap Public-Use Data Technical Document.

Release procedures for OnTheMap Public-Use Data are controlled by SOP 4211(under development).