Census geography: Bridging data for census tracts across time>>

Use the LTDB

The LTDB provides estimates using 2010 boundaries for a standard set of variables from 1970 through 2000. These data may meet the needs of many users. As an initial step, we provide two sets 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 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. 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 1970-2010. 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.


A new study that takes advantage of access to the confidential microdata in the 2000 Census in a Federal Statistical Research Data Center (FSRDC) shows substantial error in estimates of tract characteristics other than the total population count. We now provide alternative “differential privacy” (DP) estimates of a selected set of variables from that study: 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. Note, however, that for tracts that experienced no boundary change no estimation is required, and the LTDB-DP estimates include a small amount of added random noise. In these cases the original published data (also reproduced in the LTDB) are slightly more accurate. 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. Refer to the working paper (Logan, Zhang, and Stults 2020) for more details.

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, you can use LTDB tools to estimate these data within 2010 boundaries.

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 2010 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.