Where does the data come from?
The process of estimating local emissions begins with statewide fossil fuel emissions calculated from monthly data published by the U.S. Department of Energy’s Energy Information Administration and the U.S. Department of Transportation and annual data published in the State Inventory Tool and FLIGHT large facility emissions database, both created by the U.S. Environmental Protection Agency.
The statewide emissions data is converted to county values using local indicator variables to calculate each county’s share of statewide emissions. The major indicator variables include:
- Population and housing characteristics from the Census Bureau’s American Community Survey
- Employment information from the Census Bureau’s Quarterly Workforce Indicators dataset
- Vehicle miles traveled from the U.S. Department of Transportation
- Forest coverage from the National Land Cover Database (multiple agencies)
- Agriculture crop harvests and animal counts from the Department of Agriculture’s Census of Agriculture
The following pdf files provide interim information to serve as basic summaries of the major data sources, emission calculation processes, and local downscaling algorithms used in the Trackers.
Also available is the Tracker Update Documentation Manual, which provides details of the database structure, static datasets, and monthly update process. A suite of 12 R programs is run each month to download new statewide data and apply downscaling methods to calculate each local area’s share of statewide emissions.