The unmarked word American defaults to white in US usage

Evidence

Deep within the word “American” is its association with race. To identify someone as a South African is to say very little; we need the adjective “white” or “black” or “colored” to make our meaning clear. In this country it is quite the reverse. American means white, and Africanist people struggle to make the term applicable to themselves with ethnicity and hyphen after hyphen after hyphen. (Morrison, 1992:47) The existence of different types of racialized ideologies means that we cannot focus only on ideologies that have explicit racialized content - it is more complex than that. — David Theo Goldberg, John Solomos, A Companion to Racial and Ethnic Studies, 1841

Categorization

• DEFINE: Illustrates how an ostensibly neutral national label carries a racialized default in a way that the South African parallel makes concrete.
• CANDY: The South African vs. American default-adjective contrast is a crisp, shareable observation about how racialized meaning hides in plain language.