The San Francisco Bay Area has numerous streets and institutions nutamed Alemany, Portola and Serra, and a few named Alberni, Palou and Yorba. These are all Catalan surnames belonging to bigwigs (political and ecclesiastic) during the Spanish and Mexican domination of California. (Palou and Serra were Majorcans, the others Catalonians.) Elsewhere in Mexico, however, one is hard put to find Catalan surnames; they are nowhere near as common among Mexicans as they are among Cubans, Dominicans and Puerto Ricans. It appears to me, from what I have managed to find out from reading, that until the nineteenth century Catalans who went to the Indies to make their fortune tended to return home once they had made it and so did not leave many descendants in those countries that were no longer under Spanish rule. In Wikipedia’s listing of Mexican people of Catalan descent, most of the names belong to people who are twentieth-century immigrants from Spain or their immediate descendants.
But, oddly enough, Mexican Spanish seems to have more elements that correlate with Catalan than any other variety of Spanish besides that spoken in Catalonia itself. Here are some examples.
• Nomás, seemingly a calque of només, is the common word for ‘only’, not solamente or solo.
• Estimado/a, like Catalan estimat/da, is usually used for ‘dear’ in the salutation of a letter, not querido/a.
• Mande, almost the equivalent of Catalan mani’m, is the usual response to hearing one’s name called or to not catching what was said, not sí or cómo.
• Almuerzo is, as in Catalonian Spanish, the equivalent of esmorzar, a mid-morning snack, and not lunch as elsewhere.
I would need to know more than I do about the presence of Catalan-speakers in Mexico during the formative era of Mexican Spanish before I could say that these are indeed Catalanisms. Hence the question mark in the title.