The Senate agreed to the ratification of the treaty with France providing for theLouisiana Purchase. ArtistConstantino Brumidi later commemorated this treaty with the frescoed painting,Cession of Louisiana, above the doorway to S-124, then the Senate Committee on Territories, in the Capitol.

Louisiana became the 18th state admitted to the Union. In September of that year,Jean Noel Destrehan of Destrehan andAllan Bowie Magruder of Opelousas were elected to serve as the state's first U.S. senators. Destrehan resigned before being seated, andThomas Posey of Attakapas was appointed in Destrehan's place. 

Lots were drawn to determineclass assignments for SenatorsMagruder andPosey. Magruder was assigned to Class 1, with a term to expire March 3, 1813. Posey was assigned to Class 3, with a term to expire March 3, 1817.

After the Capitol wasleft in ruins from a British attack on the city of Washington, Louisiana senatorEligius Fromentin of New Orleans argued in favor of construction of an "unadorned"' Capitol, to be situated conveniently near the Georgetown area. "Our laws to be wholesome, need not be enacted in a palace," he reasoned. Congress opted to restore the existingCapitol.

James Brown of New Orleans became chairman of theSenate Committee on Foreign Relations, serving until 1820.

Henry Johnson of Donaldsonville became chairman of theSenate Committee on Indian Affairs, serving until 1823.

Josiah S. Johnston became chairman of the Senate Committee on Commerce (today'sCommittee on Commerce, Science, and Transportation), serving until 1827.

Edward Livingston of New Orleans resigned his Senate seat to become secretary of state under President Andrew Jackson. Jackson had given Livingston arecess appointment. The Senate confirmed thenomination on January 12, 1832.

Alexander Mouton of Attakapas district, now Lafayette Parish, became chairman of the Senate Committee on Agriculture (today'sCommittee on Agriculture, Nutrition, and Forestry), serving until 1841.

Pierre Soulé of New Orleans became chairman of the Senate Committee on Agriculture (today'sCommittee on Agriculture, Nutrition, and Forestry), serving until 1853.

SenatorsJudah P. Benjamin andJohn Slidell, both of New Orleans, withdrew from the Senate after Louisiana seceded from the Union on January 26, 1861. Benjamin's seat wasdeclared vacant by the Senate on March 14, 1861. Slidell's term expired on March 3, 1861, so the Senate took no formal action against him.

Both R. King Cutler and Charles Smith presented credentials to the Senate to fill the Louisiana seats that had been vacant since before the outbreak of the Civil War. At the same time, Louisiana citizens submitted a memorial to the Senate asking that Cutler and Smith not be seated. Debate in the Senate over the seating of Cutler and Smith continued through the expiration of Smith's term, at which time Louisiana governorMichael Hahn's credentials were submitted to the Senate. Ultimately, these election cases remained unresolved. It was not until the state of Louisiana was formally restored to the Union in 1868 that the state was again represented in the Senate.

Louisiana was formally readmitted to representation in Congress after the state legislature ratified theFourteenth Amendment to the United States Constitution.

Pinckney B. S. Pinchback presented his credentials to the Senate but spent the next three years in a dispute for the seat. On March 8, 1876, the Senate voted 32 to 29 not to seat Pinchback, preventing him from becoming the third African American United States senator.James B. Eustis of New Orleans was seated on December 10, 1877.

Both John Ray and William L. McMillen appeared before the Senate with certificates of election for the same Senate seat, to complete the final six weeks of the term of SenatorWilliam P. Kellogg of New Orleans, who had resigned to run for governor. The case was referred to the Senate Committee on Privilege and Elections, who heard a confusing chronicle of rival legislatures, and ultimately neither candidate was seated.

The Senate voted 30 to 28 in favor of seatingWilliam P. Kellogg following disputed elections by rival legislatures. Undaunted, Henry M. Spofford, the other claimant of the Senate seat, continued to press his claim until his death in 1880.

The Senate confirmed thenomination of SenatorEdward D. White, born in Lafourche Parish, as an associate justice of theSupreme Court. White resigned from the Senate on March 12, when he began his tenure on the Court. On December 12, 1910, White was nominated and confirmed as chief justice of the United States.

SenatorHuey P. Long of New Orleans traveled to Arkansas for an extraordinary nine-day campaign tour in support of long-shot Senate candidateHattie Caraway. The highly publicized "Hattie and Huey" tour resulted in a landslide victory for Caraway.

SenatorHuey P. Long delivered his "Every Man a King" radio address nationwide. In 1932 and 1933, the Senate had rejected Long's legislative efforts to secure a more equitable distribution of the nation's wealth. With this classic speech, Long utilized his oratorical skills and the power of radio to take his cause directly to the American people.

Following a third Senate investigation into campaign irregularities in Louisiana, the Senate Committee on Privileges and Elections concluded that no further Senate action was warranted with regard to the seating of SenatorsHuey P. Long andJohn H. Overton of Alexandria. The full Senate agreed by voice vote and Long and Overton retained their seats.

SenatorHuey P. Long began what would become his longest and most dramaticfilibuster. Long, known as "The Kingfish,"spoke for 15 hours and 30 minutes, the second-longest Senate speech to that date.

SenatorHuey P. Long was shot by an assassin in the state capitol building in Baton Rouge. Long died from his wounds two days later.

Rose McConnell Long of New Orleans was appointed to fill the vacancy caused by the death of her husband, SenatorHuey P. Long, becoming only thethird woman to serve in the U.S. Senate and the first woman senator from Louisiana. She was subsequently elected in a special election and served until January 3, 1937.

SenatorAllen J. Ellender of Montegut deliveredGeorge Washington's Farewell Address on the floor of Senate, a tradition dating to 1862.

Astatue ofHuey P. Long, by artist Charles Keck, was unveiled in the U.S. Capitol, becoming Louisiana's first contribution to theNational Statuary Hall Collection.

Russell B. Long of Shreveport was elected to fill the vacancy caused by the death of SenatorJohn H. Overton. In doing so, Long became the first senator whose father (Huey P. Long) and mother (Rose McConnell Long) had also served in the Senate.

Allen J. Ellender became chairman of the Senate Committee on Agriculture and Forestry (today'sCommittee on Agriculture, Nutrition, and Forestry), serving from 1951 to 1953, and again from 1955 to 1971.

Felton M. "Skeeter" Johnston, who was born in Tallulah but later lived in Mississippi, was elected to serve as thesecretary of the Senate, a position he held for more than 10 years.

Abronze statue ofEdward D. White, former senator and chief justice of the United States, by artist Arthur Morgan, was unveiled in the U.S. Capitol, becoming Louisiana's second contribution to theNational Statuary Hall Collection.

Russell B. Long was elected Senate Democratic Partywhip, serving until 1969.

Russell B. Long became chairman of theSenate Committee on Finance, serving until 1981.

Allen J. Ellender became chairman of theSenate Committee on Appropriations, serving until 1972.

Allen J. Ellender was electedpresident pro tempore of the Senate, serving until July 27, 1972.

Elaine S. Edwards of Marksville became the 11thwoman to serve in the Senate and Louisiana's second woman senator when she was appointed by the governor, her husband, to fill the vacancy caused by the death of SenatorAllen J. Ellender.

SenatorRussell B. Long became Louisiana'slongest-serving senator, surpassingAllen J. Ellender's record of 35 years, 5 months, and 26 days. Long went on to serve a total of 38 years and 3 days.

J. Bennett Johnston of Shreveport, Caddo Parish, became chairman of theSenate Committee on Energy and Natural Resources, serving until 1995.

SenatorJohn B. Breaux of Crowly received theGolden Gavel Award for presiding over the Senate 100 hours in a single session.

SenatorMary L. Landrieu of Baton Rouge (and later New Orleans) deliveredGeorge Washington's Farewell Address on the floor of the Senate, a tradition dating to 1862.

SenatorJohn B. Breaux of Crowly deliveredGeorge Washington's Farewell Address on the floor of the Senate, a tradition dating to 1862.

SenatorDavid Vitter of Metairie received theGolden Gavel Award for presiding over the Senate 100 hours in a single session.

Mary L. Landrieu, Louisiana's third woman senator, became chairman of theSenate Committee on Small Business and Entrepreneurship, serving until February 2014.

Mary L. Landrieu became the first woman to chair theSenate Committee on Energy and Natural Resources, serving until 2015.

David Vitter became chairman of theSenate Committee on Small Business and Entrepreneurship, a position he held until 2017.

SenatorBill Cassidy of Baton Rouge received theGolden Gavel Award for presiding over the Senate 100 hours in a single session.

SenatorBill Cassidy became chairman of theSenate Committee on Health, Education, Labor, and Pensions.