English: White population of the United States in the first U.S. Census in 1790, classified by national origin according to a 1909 preliminary estimate published in A Century of Population Growth From the First to the Twelfth Census of the United States: 1790-1900 (top half) and revised totals following comprehensive study published two decades later in the American Council of Learned Societies Report of the Committee on Linguistic and National Stocks of the United States (bottom half). The latter was commissioned upon passage of the Immigration Act of 1924, which tasked the Census Bureau with computing the National Origins Formula—whereby immigration would be regulated by quotas in proportion to the share of blood each nationality contributed to the total White American population as of the 1920 Census—necessitating more accurate analysis given the actual consequences: affecting size of quotas apportioned to each country when the national origins system took effect in 1929. The estimated proportional makeup of the U.S. population in 1790 was then projected onto their descendants (termed “colonial stock”) to classify the national origins of what amounted to 45% of Americans in 1920. Demographers combined this with 21.6% who were the grandchildren or later-generation descendants of post-colonial immigrants, and 1/3 who were immigrants or children of immigrants, to arrive at estimates of the national origins of the entire White American population in 1920.