Andrew J. Kellar was born in 1838 to Sarah (Conley) and George Kellar in Tennessee. He practiced law in Tennessee until enlisting with the Confederate army in 1861 at the beginning of the Civil War. Following the war, he resumed his law practice as well as began work in politics. In 1865, he married Margaret Chambers. He was a close friend and supporter of Andrew Johnson. In 1893, Kellar relocated to South Dakota.

Andrew Johnson served as the seventeenth president of the United States. Johnson settled early in his life in Greeneville, Tennessee; he was educated as an attorney and later served in the Tennessee General Assembly. Johnson further served in the offices of governor of Tennessee, U. S. Representative and U. S. Senator. He served as Vice-President of the United States during the Civil War. Upon Lincoln's assassination, Johnson became the new president; however, he and Congress clashed over control during the Reconstruction Era, and in 1868, the House Republicans in Congress impeached Johnson, the first president to face impeachment. Johnson's presidency was spared by a single vote in the Senate. After leaving the White House, Johnson uncharacteristically returned to politics, and he served as a Tennessee Senator before dying from a stroke in 1875.