Eureka, CA has a population of 27,002 and is the 1,602nd largest city in the United States. The population density is 2,877 per sq mi which is 1138% higher than the California average and 3076% higher than the national average. The median age in Eureka is 37 which is approximately 3% higher than the California average of 36. In Eureka, 44% of the population over 15 years of age are married, 87% speak English and 6% speak Spanish. 66% of Eureka residents were born in California, 27% were born out of state, 1% were born outside of the United States and 7% were foreign born.