S: WaPo – https://wapo.st/2B0fldb (last access: 24 January 2019); Newsweek – https://bit.ly/1obTgw3 (last access: 24 January 2019).
N: 1. wetback (n.): “illegal Mexican immigrant to the U.S.,” c.1924, from wet (adj.) + back (n.); from notion of wading the Rio Grande.
2. First use: 1929. Origin: the practice of wading or swimming the Rio Grande where it forms the U.S.-Mexico border.
3. First use: 1920s. Origin: so named from the practice of swimming the Rio Grande to reach the United States.
4. A Mexican who enters the U.S. illegally (as by wading or swimming the Rio Grande).
5. Wetbacks willing to work for nothing if a rancher would conceal them.
S: 1. OED – https://bit.ly/2WcjRyg (last access: 3 September 2014). 2. MW – https://bit.ly/2DxPew5 (last access: 22 March 2014). 3. OD – https://bit.ly/2UcYgnK (last access: 22 March 2014). 4 & 5. TERMIUM PLUS (last access: 22 March 2014).
CR: boat people, emigrant, immigrant, immigration, refugee, small boat.