Rancho Cucamonga, CA has a population of 173,309 and is the 145th largest city in the United States. The population density is 4,333 per sq mi which is 1765% higher than the California average and 4683% higher than the national average. The median age in Rancho Cucamonga is 36 which is approximately equal to the California average of 36. In Rancho Cucamonga, 54% of the population over 15 years of age are married, 66% speak English and 19% speak Spanish. 62% of Rancho Cucamonga residents were born in California, 16% were born out of state, 1% were born outside of the United States and 21% were foreign born.