Lamar County is located in west central Georgia between Atlanta and Macon. In 1920, the session of the state transferred land from Monroe and Pike counties and created the county of Lamar, making a land area for Lamar County of 185 square miles.

Lamar County has a rolling landscape and is well drained by streams emptying into the Flint River and Ocmulgee River. Its agricultural land, with pecan and peach groves, is a little northwest of the geographic center of Georgia. About 2.3 percent of Lamar's residents are currently involved in agriculture, forestry, fishing, hunting, and mining.

The county seat, Barnesville, was well known as the "Buggy Capital of the South" in the late 1800s and early 1900s, with several Barnesville companies producing buggies. In mid-September each year, Barnesville celebrates Buggy Days with a parade—displaying original Barnesville Buggies—and a crafts celebration bringing thousands of visitors to the town.

Population in the county has grown from the 1930 census figure of 9,745 to 15,912 in the 2000 census. Future plans of the Atlanta Regional Commission are to include Lamar County in the Atlanta metropolitan area.

Gordon College is located in Barnesville, and more than 3,000 students were enrolled in 2003. In 1972 the college became a two-year unit of the University System of Georgia.

The Barnesville Expo Center offers a wetlands trail with an open arena. The center, used for trade shows and educational programs as well as livestock events, is the first in the nation to combine wetlands and an expo center. Lamar County is investing in its future to provide environmental and agricultural education for its youth.