1920, Temporary admission of illiterate Mexican laborers: Hearings before the Committee on Immigration and Naturalization, House of Representatives, 66th Congress, 2nd Session, p. 141,
Mr. HUDSPETH. […] I stood here and did all in my power to keep the “wetback” […] from coming across. And I stand here to-day asking for that.
The CHAIRMAN. […] What is a “wetback”?
Mr. HUDSPETH. You have heard a “wetback” described; he is a fellow that crosses the river surreptitiously.

The charges against the U.S. had cited cases of peonage and labor under forced contracts in Maine, Connecticut, Texas, Arkansas, Georgia and California. They had revealed that thousands of “wetbacks” (i.e., Mexican laborers who wade the Rio Grande in search of work in the U.S.) lived in squalor and poverty, sometimes were paid as little as $8 a week.

He went through a couple of bottles of wine and made a speech denouncing wetbacks and Asian immigrants.

A successful wetback, the limo driver was thinking—that was his assessment of his Mexican-American passenger.

Wetback

Meaning

Noun