Plains has yet to put a famous person on the list
Famous people are on record for 93 of the towns in Montana. The longest list in Montana is Missoula’s, with 70 names. Billings has the second-longest list in Montana, after Missoula, with 65.
Who’s listed here
Famous people come from Wikidata (people whose birthplace is Plains), checked against each person’s English Wikipedia article and ranked by how many Wikipedia languages cover them. Nobody born in Plains has passed that check yet, and nobody born within 35 miles is listed.
From Wikidata and Wikipedia: people whose birthplace is Plains and whose English Wikipedia article agrees, ranked by how many Wikipedia languages cover each person. People known mainly for crimes, and adult performers, aren’t listed. “The usual town” = everyone born in the towns gathered so far.