This report shares an analysis of data nonresponse to the citizenship question on the American Community Survey. Nonresponse rates vary by demographic group, but have been rising over time–showing an increased sensitivity to the question. It is expected that the nonresponse rate to the citizenship question on the 2020 Census will be even higher that the 6% nonresponse rate to the question on the ACS, and that the question will make the census more expensive and it’s results less accurate.