[5] It is known as the birthplace of Harry S. Truman, the 33rd president of the United States.

It was named for Mirabeau B. Lamar, second president of the Republic of Texas.

[8] The city suffered multiple attacks by rebels during the Civil War.

It was considered to be a sundown town prior to the Civil Rights era.

[9] Lamar is located in central Barton County adjacent to a bend in the North Fork Spring River and lies on US Route 160 just east of US Route 71.

[11] At the 2010 census there were 4,532 people, 1,866 households, and 1,202 families living in the city.

There were 2,099 housing units at an average density of 410.0 per square mile (158.3/km2).

At the 2000 census there were 4,425 people, 1,835 households, and 1,154 families living in the city.

Lamar Municipal Airport (LLU) serves the city and surrounding communities.