The LTDB includes two kinds of files. The "full count" files include the key variables from Census 2010 (race and Hispanic origin, age by race and Hispanic origin, household composition, and housing occupancy and tenure), with comparable variables from the censuses in 1970-2000 (and the race counts from 2020) that have been adjusted to 2010 boundaries. The "sample count" files include a wide range of other variables based on sample data -- the one-in-six samples from the decennial census in 1970-2000 and the sample data from the American Community Survey for 2008-2012 and 2015-2019. These include variables such as socioeconomic characteristics that are widely used by researchers.
On the LTDB download page you will find a codebook that identifies the original tables in each census year from which data have been taken. You will also find the standard harmonized data set for 1970-2020. For reference, we provide the five individual data files that include the original tract IDs and data for each decade. CLICK HERE for the download page.
For a few variables in 2000 we are able to provide more accurate estimates in 2010 boundaries. These are the variables described in Logan et al (2021) that were approved for disclosure by the Census Bureau: population, % non-Hispanic white, % under 18, % homeowner, % college-educated, and median household income. We recommend use of these 2000 estimates whenever possible because they are very close to the “true” values. CLICK HERE for the download page for the LTDB-DP. The download includes a single spreadsheet for all 70,000+ census tracts, with a worksheet that defines the variables in it.
THE LTDB ALSO INCLUDES OTHER FUNCTIONS:
1. INPUT YOUR OWN DATA . If you have data aggregated to census tract boundaries for any of the decades 1970-2000 and 2020, you can use LTDB tools to estimate these data within 2010 boundaries. For 1970-2000, the procedure is automated. To harmonize data in 2020 tract boundaries to 2010 tract boundaries, we provide a downloadable crosswalk file that shows the correspondence between blocks in 2020 with tracts in 2010.
2. BACKWARDS LTDB. If you have 2010 data that you want to analyze along with other data for 2000, you can use this tool to convert backwards. This system provides a STATA program and a crosswalk file that links the 2000 and 2010 boundaries. You must provide your own 2000 data in STATA format. Consult the "INPUT YOUR OWN DATA" SECTION to learn how to use the STATA file and what issues to be aware of.