The U.S. Census Bureau has a long history of conducting research to improve questions and data on race and ethnicity. Since the first census in 1790, the Census Bureau has collected information on race and ethnicity. The census form has reflected changes in society and shifts that have occurred in the way the Census Bureau classifies race and ethnicity. Since the 1970s, the Census Bureau has conducted content tests to research and improve the design and function of different questions, including questions on race and ethnicity. Additionally, the Census Bureau collects race and ethnic data following U.S. Office of Management and Budget (OMB) guidelines.

The Census Bureau also tests the wording of questions to ensure census questionnaires are easily understood and reflect the population accurately. In the last decade, Census Bureau researchers observed possible confusion about and misreporting of racial or ethnic identity in the current questions that asks Hispanic origin and race in two separate questions. During tests in 2010 and 2012, we experimented with changes to the race and Hispanic origin questions that combined the separate questions about Hispanic origin and race into one question. The Census Bureau continued to evaluate this change in the 2014, 2015, 2016, and 2017 Census Tests. The 2015 National Content Test was another opportunity to compare different design options for race and ethnicity prior to making final decisions about the content for the 2020 Census.

The Census Bureau is also exploring and testing ways to collect and tabulate data for people of Middle Eastern or North African (MENA) heritage. In the 1990s, as part of the public comment process prior to OMB developing the 1997 OMB Standards on collecting data on race and ethnicity, OMB received a number of requests to add an ethnicity category for Arabs and Middle Easterners to the collection standards. At that time, OMB encouraged further research on how to collect and improve data on this population. Since then, community leaders and advocacy groups have reached out to the Census Bureau and to OMB on conducting such research. The 2015 NCT included research to explore the best ways to collect and tabulate data for respondents of Middle Eastern or North African (MENA) heritage.

Additionally, the Census Bureau does research on other content topics; however, they are not governed through the same OMB standards on collecting data as the OMB guideline on collecting data on race and ethnicity. The 2014 and 2015 Census Tests tested new response categories for opposite-sex and same-sex husband/wife/spouse and unmarried-partner relationships. The Census Bureau tested variations of those proposed changes in the Internet and paper data collection questionnaires.