"America must remain American," President Calvin Coolidge said in 1924 as he signed into law a measure that ended a period of nearly unrestricted immigration into the United States. The importance of the 1924 Immigration Act—sometimes referred to as the Johnson-Reed, National Origins, or Japanese Exclusion Act—is well known. But the story of how it highlighted race as an important identifier of Americanness is less well understood, though many appreciate its significance. Not only did this first permanent act restricting immigration determine how many arrived, it created, as Coolidge hinted, a racial narrative through which the genius of the country, the strength of its people, and its history and its accomplishments were understood. The 1924 restrictions on immigration clarified and strengthened the racial requirements for citizenship embedded in naturalization statutes since 1790.