Rio Oso has no famous person on record yet
Modesto has the most of any town in California: 65. After Modesto, the next longest list in California is Alameda’s, with 64. 549 towns in California have at least one famous person on record.
Who’s listed here
Famous people come from Wikidata (people whose birthplace is Rio Oso), checked against each person’s English Wikipedia article and ranked by how many Wikipedia languages cover them. Nobody born in Rio Oso has passed that check yet, and nobody born within 35 miles is listed.
From Wikidata and Wikipedia: people whose birthplace is Rio Oso 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.