Although impressive, Sen. Rand Paul's 13-hour filibuster over the nomination of John Brennan as CIA director wasn't the longest in history. But it was a rare example of the lengths senators will go to make sure they're heard.
A filibuster is a tactic used, in this case by a U.S. senator, to delay or block a vote on legislation or an appointment. Lawmakers can keep a debate going without interruption indefinitely.
They don't have to specify what they are filibustering but must keep speaking or, in the case of one senator on the list, singing.
Here are some of the most memorable and longest filibusters in Senate history.
24 hours, 18 minutes: Sen. Strom Thurmond of South Carolina holds the record for the longest filibuster when he took to the floor to oppose the Civil Rights Act of 1957. One of the ways the segregationist Republican filled his time was by reading the election laws of every state. Hulton Archive/Getty Images
22 hours, 26 minutes: Sen. Wayne Morse was considered "The Tiger of the Senate" by his admirers. He abandoned the Republican Party and became an Independent because of President Dwight Eisenhower's decision to choose Richard Nixon as his running mate. In 1953, Morse filibustered Tidelands Oil legislation, which was the record until Thurmond broke it in 1957. George Skadding//Time Life Pictures/Getty Images
18 hours: Sen. Robert La Follette Sr. was a progressive Republican who often championed causes of the working class and working poor. Like others on this list, La Follette knew how to attract attention. For instance, his 18-hour filibuster in 1908 stood as the record until Morse outlasted him 45 years later. Keystone View Company/FPG/Archive Photos/Getty Images
16 hours, 12 minutes: In 1981, the country was amassing debt and commentators were warning of financial apocalypse. Sen. William Proxmire, a Democrat from Wisconsin, filibustered against allowing the national debt to go over $1 trillion. Currently, the national debt is over $5 trillion. Terry Ashe//Time Life Pictures/Getty Images
15 hours, 30 minutes: Sen. Huey Long of Louisiana filibustered a provision in President Franklin D. Roosevelt's National Recovery Administration in 1935. The Democrat had a reputation as a showman and used up some of his time on the floor by reading out recipes for a friend's oysters and potlikkers Fotosearch/Getty Images
15 hours, 14 minutes: Sen. Alfonse D'Amato was somewhat of an oddity. The New York Republican was a conservative in a typically liberal state and very blunt and sometimes theatrical. Near the end of his filibuster of a pending tax increase, he chose to sing until finally giving up. J. DAVID AKE/AFP/Getty Images