James Paul "Buck" Buchanan (April 30, 1867 – February 22, 1937) served as U.S. Representative from the 10th district of Texas from 1913 until his death on February 22, 1937.
Later in 1889, Buchanan began a law practice in Washington County, and almost immediately became involved in politics as a Democrat. He served as a county justice of the peace from 1889 to 1892, and as the county's prosecuting attorney from 1892 to 1899. From 1899 to 1906, Buchanan was the district attorney for the twenty-first judicial district.
Buchanan was a member of the Texas House of Representatives from 1906 to 1913. In 1913, he was elected to the Sixty-third Congress, filling the vacancy left by the resignation of Albert Sidney Burleson. Buchanan was elected to a full term in the Sixty-fourth Congress, and won reelection eleven times. He served in the US House from April 15, 1913 to February 22, 1937, and was the chairman of the House Committee on Appropriations from 1933 until his death.
He was succeeded in Congress by Lyndon B. Johnson, then the head of the National Youth Administration in Texas and an ardent New Dealer, who later became the 36th President and vice president of the United States.