For the first time in 27 years, the U.S. government is changing how it categorizes people by race and ethnicity, an effort that federal officials believe will more accurately count residents who identify as Hispanic and of Middle Eastern and North African heritage.

The revisions to the minimum categories on race and ethnicity, announced Thursday by the Office of Management and Budget, are the latest effort to label and define the people of the United States. This evolving process often reflects changes in social attitudes and immigration, as well as a wish for people in an increasingly diverse society to see themselves in the numbers produced by the federal government.