Martinez is a city located in Contra Costa County California. It is also the county seat of Contra Costa County. With a 2020 population of 38,079, it is the 212th largest city in California and the 1032nd largest city in the United States . Martinez is currently declining at a rate of -0.29% annually but its population has increased by 6.29% since the most recent census, which recorded a population of 35,824 in 2010. Martinez reached it's highest population of in . Spanning over 14 miles, Martinez has a population density of 3,015 people per square mile.
The average household income in Martinez is $128,788 with a poverty rate of 5.13%. The median rental costs in recent years comes to $1,728 per month, and the median house value is $596,400. The median age in Martinez is 42.6 years, 40.6 years for males, and 44.9 years for females.