William Bankhead was the 42nd Speaker of the House of Representatives under the presidency of Franklin D. Roosevelt.

In 1898, Bankhead became city attorney of Huntsville, serving until 1902. In 1900, he was elected to the Alabama House of Representatives for one term, serving through 1901. In 1910, Bankhead was appointed solicitor of the fourteenth judicial circuit of Alabama, serving until 1914.

In 1914, William sought the Democratic nomination for U.S. Representative, but did not get it. In 1916, he was elected Representative from the newly created 10th Congressional District. Bankhead held the 10th District until it was abolished after the 1930 Census, when Alabama lost a seat. He was the only person ever elected from the 10th District.

After reapportionment and redistricting following the 1930 Census, Bankhead was re-elected Representative from the 7th District in 1932, and was re-elected three times, serving until his death in 1940. In 1934, he was chosen House Majority Leader by his fellow Democrats. On June 4, 1936, he was chosen Speaker of the House to succeed Jo Byrns, who had died that morning. Bankhead served as Speaker until his own death in office on September 15, 1940.

As Speaker, Bankhead held the highest political office of any Alabamian save Vice President William R. King.

At the 1940 Democratic National Convention (three months before his death), he finished 2nd to Henry A. Wallace on the Vice Presidential ticket, losing the delegate count 626-329.