Signal Hill, CA has a population of 11,404 and is the 3,558th largest city in the United States. The population density is 5,210 per sq mi which is 1935% higher than the California average and 5651% higher than the national average. The median age in Signal Hill is 33 which is approximately 8% lower than the California average of 36. In Signal Hill, 44% of the population over 15 years of age are married, 51% speak English and 32% speak Spanish. 54% of Signal Hill residents were born in California, 15% were born out of state, 1% were born outside of the United States and 31% were foreign born.