After several attempts to secure a new county, the city fathers were successful in bringing the issue before the State Legislature. In August of 1920, the representatives of Barnesville went by train to Atlanta to await the vote. The monies had been paid and the vote was taken. It was defeated narrowly. The men came back to Barnesville that evening on the down train and held a town meeting. After "passing the hat," the men returned to Atlanta the next morning. Another meeting took place with the "committee" and the issue was called to a vote again. This time the bill passed creating the new county of Lamar. The county seat was to be in Barnesville. The eastern portion of Pike County and the western portion of Monroe County were to make up the new county. The historic vote was on August 17, 1920. The new county would begin operating as a legal entity on January 1, 1921. The M. W. Smith building across from the depot housed the county offices and court was held in the third floor ballroom. The area was leased from the Pinta Lodge # 88. Business was conducted here until the courthouse was completed in 1933. The courthouse was built by the local Barnesville Planing Mill with L.C. Wachendorff of Atlanta as architects. The cornerstone was laid in 1931 by the Pinta Lodge # 44. This lodge is the oldest, continuously operating organization in Barnesville. It was chartered in 1849 and has continued to be an active and positive force in promoting and supporting the community.
During this period, the state operated A & M School was discontinued and Gordon College moved to the A & M campus. This move gave Gordon nearly 400 acres and room to grow.
The depression was difficult for all communities including Barnesville. Many people were out of work and as businessmen drew near retirement age, many firms dissolved.
The WPA brought work to many local men. A golf course was laid out, bridges were built, and streets were paved in town. The brass WPA markers can still be seen in the middle of the streets that were paved under Roosevelt's WPA program.
In August of 1938 President Roosevelt came to town via train to "throw the switch" and begin the rural electrification of rural America. This was Roosevelt's pet project, and he chose Barnesville as the site to turn on the rural electrification. Thousands of people came to town to see and hear the President. The ceremony took place on a constructed, raised platform at Summers Field.
World War II brought the Barnesville Blues into action again. This local unit had begun at the time of secession. In times of peace it would deactivate and in times of war would become active and begin to train again. The Blues always served with honor and distinction. The last commanding officer, Brigadier General Homer Sappington had the honor of having the present National Guard unit in Barnesville named after him.