Lamar is a city located in Barton County Missouri. It is also the county seat of Barton County. With a 2020 population of 4,268, it is the 154th largest city in Missouri and the 5227th largest city in the United States . Lamar is currently declining at a rate of -0.30% annually and its population has decreased by -5.83% since the most recent census, which recorded a population of 4,532 in 2010. Spanning over 6 miles, Lamar has a population density of 819 people per square mile.
The average household income in Lamar is $49,764 with a poverty rate of 29.68%. The median rental costs in recent years comes to $561 per month, and the median house value is $89,600. The median age in Lamar is 41.6 years, 39 years for males, and 46 years for females.