Westmont, CA has a population of 32,147 and is the 1,324th largest city in the United States. The population density is 17,399 per sq mi which is 7387% higher than the California average and 19104% higher than the national average. The median age in Westmont is 31 which is approximately 14% lower than the California average of 36. In Westmont, 35% of the population over 15 years of age are married, 53% speak English and 45% speak Spanish. 60% of Westmont residents were born in California, 14% were born out of state, 1% were born outside of the United States and 25% were foreign born.