from some
some obscure discussion board I found:
Well, there's the official version and then there's the more colorful, might-be-true version. Here's the official version straight from RC's website: The name "Cucamonga" comes from the Shoshonean Indian word kukamonga, which means "sandy place."
That might make sense, but Cucamonga was originally called Cocomango by the Indians and it was the Spanish that changed it to Cucamonga when the land grant was drawn up. No one I know had ever heard the official version until it just magically appeared during the late 70s when there was a battle of what to name the city as there was a push on to combine and incorporate the areas of Cucamonga, Etiwanda and Alta Loma.
In old writings of the Californios, you'll find the Cocomango spelling frequenlty enough to think that may have been in common usage among the regular folks. Not many of those documents are online, but I did find this one at the Library of Congress from 1862 on page 261 of Judge Benjamin Hayes' diaries: Jan. 10th: Jonathan R. Scott, Esq., one of our leading attorneys, informs me that on the 8th inst., an officer and twenty men appeared at the rancho of Coco-Mango, San Bernardino county, for the purpose of arresting John Rains, Esq., the proprietor.
»memory.loc.gov/cgi-bin/query/r?ammem/c..)
I spent a lot of time at the San Bernardino County Museum as a kid and the experts there said Cocomango was a combination of Indian words that basically translated to "place of VERY friendly women". That may have just been a story made up by some historians to have a little fun at the expense of a hick kid, but it's as likely to be true as the official version. But I had so much fun at my favorite bar in Cucamonga (Club 66 on Foothill Blvd) back in the 70s that I'm leaning more toward Place of VERY Friendly Women than Sandy Place. Besides, anyone who's ever dug a hole there knows it's more rocky than sandy.