This discussion however, started me thinking about how these terms originated, such as "immigrant." It seems that at the time of the founding of the United States, the more common words to describe recent entrants were words such as "alien," "foreigner," and "newcomer."
The Oxford English Dictionary reports that the pioneering American historian Jeremy Belknap was one of the first to use "immigrant" and its cognates in print. In his History of New Hampshire (1792), vol. 3, preface, 6, Belknap wrote, "There is another deviation from the strict letter of the English which is found extremely convenient in our discourses on population . . . The verb immigrate and the nouns immigrant and immigration are used without scruple in some parts of this volume."
The used of "immigrant" appears to have become frequent only after the heavy transatlantic movements of people to North America. After the onset of mass immigration to the United States, which began in the 1840s, the term became routine.