Changes to Census Bureau Data Products

Open Letter to Census Bureau

Please add your name to our letter to preserve usable American Community Survey public data products. We are seeking clarification and engagement with the research community from the Census Bureau.

Our open letter requests:

  1. A public timeline for changes to the ACS summary files and microdata.
  2. Engagement with the research community in advance of any changes.
  3. Public versions of new noise-infused ACS summary files and microdata for 2005-2017 so that researchers can assess their usefulness by replicating existing studies.

Census Bureau Disclosure Control

In September 2018, the Census Bureau announced a new set of methods for disclosure control in public use data products, including aggregate-level tabular data and microdata derived from the decennial census and the American Community Survey (ACS). The new approach, known as differential privacy, “marks a sea change for the way that official statistics are produced and published” (Garfinkel, Abowd, and Powazek 2018).

The Census Bureau claims that the new system will be more open and transparent to users. But the new system will come with a significant trade-off in data accuracy, making the public data useless for many applications. Indeed, in its pure form differential privacy techniques could make the release of scientifically useful microdata impossible and severely limit the utility of tabular small-area data.

We are following this conversation, and we will share relevant information from the Census Bureau and others as it is released.

We will continue to gather relevant information for the IPUMS user community and post here and share via IPUMS Twitter.


The Census Bureau is testing their methods on 1940 census data and they plan to release algorithms allowing registered IPUMS users to download and test them. Data are available and we will link to Census Bureau algorithms when available.