History of Congress and the Capitol

This is the story of one of the world's great experiments in government by the people.

For more than two centuries, a new Congress has convened every two years following elections that determine all the seats in the House and one-third of those in the Senate. While the individuals change, the institution has endured-through civil and world wars, waves of immigration and great migrations, and continuous social and technological change.

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Unprecedented growth in the 1850s strained the fragile agreements that had kept the nation united, but had also kept it part slave, part free. The addition of each new state to the Union rattled the delicate political balance carved out by compromises in Congress. In 1854, the Kansas-Nebraska Act allowed residents of each of these new territories, rather than Congress, to decide whether to permit slavery. While intending to keep the nation together, this act inflamed sectional tensions, producing open warfare between pro- and antislavery forces in Kansas, and led directly to the Civil War.

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All Compromise Fails

Secession of Southern states and the outbreak of war fostered unity among those who remained in Congress. Senators passed bills to meet wartime emergencies and spur economic development.

After the Civil War, the Senate’s large Republican majority aimed to set policies for reconstructing the South and protecting freed slaves, and members hotly disputed President Andrew Johnson’s more lenient policies toward the former rebels. This power struggle led the House to impeach Johnson. He was acquitted at his Senate trial by one vote.

Conflicting Loyalties

War brought rapid change to Congress. By 1862, the Senate had expelled 14 members for disloyalty to the Union. It also created a loyalty oath to ensure that former Confederates could not simply return to national office. During postwar Reconstruction, when newly readmitted Southern states again elected senators, Mississippi elected the Senate’s first two African-American members.

Emotions Boil Over, 1856  - 1856

Tensions ran high over the question of slavery in the Western territories when Senator Charles Sumner rose to speak in 1856. The Massachusetts abolitionist let loose a fiery speech, denouncing expansion of slavery into Kansas. He attacked pro-slavery opponents by name—including Senator Andrew Butler of South Carolina.

Several days later, on May 22, Representative Preston Brooks, a relative of Butler’s, found Sumner sitting at his Senate desk. Raising his gold-headed walking stick, Brooks struck the Massachusetts senator repeatedly. Badly wounded, Sumner was unable to return to the Senate full-time for three years. His empty desk stood as a powerful symbol of the increasing North–South antagonism, an omen of the looming Civil War. Brooks resigned his House seat but was immediately reelected— then died shortly after.

"Sir, to assail a member of the Senate ... 'for words spoken in debate,' is a grave offense."
—Senator Henry Wilson of Massachusetts, May 23, 1856

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The Union Divides, 1861  - 1861

Rarely has a presidential election brought such immediate consequences. Abraham Lincoln’s victory in 1860 triggered the secession of America’s Southern states even before the new president took office in March of 1861. On January 21, senators from Alabama, Florida, and Mississippi rose to bid their Senate colleagues farewell. The last to speak was Jefferson Davis of Mississippi. In an emotional address before a hushed Senate, Davis defended secession, insisting that Mississippians were only exercising their rights.

Within weeks, Fort Sumter fell to the Confederacy. Union soldiers, sent to protect Washington, camped out in the Senate Chamber while the Senate was adjourned. In a flash of anger, one soldier tried unsuccessfully to demolish the desk that had once been assigned to Davis. Americans of all regions recognized clearly that the nation stood at a dangerous crossroads.

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Lawmakers, Loyalty and the "Ironclad Oath," 1864  - 1864

The Constitution requires all government office-holders to take an oath to support that document, but it establishes a specific oath only for the president. In 1789, Congress drafted a simple 14-word pledge. No one felt anything more was needed—until the Civil War.

In 1862, Congress adopted the "Ironclad Test Oath." Civil servants and military officers had to swear loyalty to the Union and affirm no previous disloyalty—a clause aimed at Confederate sympathizers. Senators didn’t have to take the oath, but many did.

Angered by those who refused, Massachusetts Senator Charles Sumner promoted an 1864 Senate rule making the new oath mandatory. Four years later, to encourage reunification, Congress created an alternative pledge for Southerners. Finally, in 1884, lawmakers replaced the wartime oath with the one used today.

"I , _________, do solemnly swear (or affirm) that I will support and defend the Constitution of the United States against all enemies, foreign and domestic; that I will bear true faith and allegiance to the same; that I take This obligation freely, without any mental reservation or purpose of evasion; and that I will well and faithfully discharge the duties of the office on which I am about to enter: So help me God."
— Oath of office, version instituted in 1884 and still in use today

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A President on Trial  - 1865

The bullet that felled Abraham Lincoln in 1865 made Andrew Johnson president. The new chief executive backed a plan for quickly reintegrating the former Confederate states into the Union. Congress’s more radical Republicans demanded stronger measures to punish rebellious states and protect the rights of freed slaves. The dispute boiled over when Johnson prepared to dismiss a cabinet member who had strong congressional support.

Overriding Johnson’s veto, Congress passed legislation denying the president’s power to remove officials without Senate consent. Johnson ignored the act, provoking impeachment by the House and a Senate trial. On May 16, 1868, seven Republican senators defied party leaders, voting with the 12 Democrats to acquit Johnson of “high crimes and misdemeanors”—by a one-vote margin. Ironically, Johnson returned to Washington in 1875 as a senator, the first former president to serve in the chamber.


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Additional information for The Senate - 1851-1877

  • Charles Sumner 1811–1874, Massachusetts

    Sumner spoke passionately for emancipation. But he paid dearly for his advocacy. A House member severely beat Sumner because of the senator's caustic references to pro-slavery members, including a relative of his assailant. After a lengthy recovery, Sumner returned to the Senate and sponsored the first law to secure the equal rights of all citizens.

  • Stephen Arnold Douglas, photograph by James Earle McClees and Julian Vannerson, ca. 1859

    NPG.77.262 National Portrait Gallery, Smithsonian Institution

  • Blanche K. Bruce 1841–1898, Mississippi

    Born into slavery in Virginia, Bruce fled north to freedom during the Civil War. Following emancipation, he pursued a career in education and politics in Missouri and Mississippi. Becoming a U.S. Senator in 1875, Bruce was the first African American to preside over the Senate in its practice of rotating Presiding Officers.

  • Roscoe Conkling, photograph by John F. Jarvis, ca. 1876

    Roscoe Conkling, photograph by John F. Jarvis, ca. 1876

    NPG.79.213 National Portrait Gallery, Smithsonian Institution

  • Senate Chamber, 1867

    Senate Chamber, 1867

    The more spacious Senate Chamber that opened in 1859 reflected the greater role of Congress in addressing the needs of a growing nation.

    Architect of the Capitol

  • Certificate of Election for Senator Hiram Revels, 1870

    Hiram Revels of Mississippi was the first African-American senator, but served just a little more than a year. An ordained minister, Revels recruited African-American troops during the Civil War and organized churches and schools.

    Records of the U.S. Senate, National Archives and Records Administration, Washington, D.C.