King Coal by Upton Sinclair

Hal made the move at once, sacrificing part of a month's board, which Reminitsky would charge against his account with the company. But he was willing to pay for the privilege of a clean home and clean food. To his amusement he found that in the eyes of his Irish friends he was losing caste by going to live with the Minettis. There were most rigid social lines in North Valley, it appeared. The Americans and English and Scotch looked down upon the Welsh and Irish; the Welsh and Irish looked down upon the Dagoes and Frenchies; the Dagoes and Frenchies looked down upon Polacks and Hunkies, these in turn upon Greeks, Bulgarians and "Montynegroes," and so on through a score of races of Eastern Europe, Lithuanians, Slovaks, and Croatians, Armenians, Romanians, Rumelians, Ruthenians -- ending up with Greasers, niggers, and last and lowest, Japs.

It was when Hal went to pay another call upon the Rafferties that he made this discovery. Mary Burke happened to be there, and when she caught sight of him, her grey eyes beamed with mischief. "How do ye do, Mr. Minetti? " she cried.