1787: On July 16 , Framers of the Constitution created a bicameral legislature in which the Senate represents all states equally, while the House represents states in proportion to their respective populations.
1790: On December 6 , Congress began a ten-year residence in Philadelphia, pending construction of a national capital in Washington, DC.
1794: On February 28, the Senate declared void the election of Albert Gallatin of Pennsylvania, the first contested election in Senate history. The Pennsylvania state legislature elected Gallatin to the United States Senate and he took the oath of office on December 2, 1793, but a petition filed with the Senate on that day alleged that Gallatin failed to satisfy the Constitutional citizenship requirement. On February 28, 1794, the Senate determined that Gallatin did not meet the citizenship requirement and declared his election void.
1795: The Senate approved Jay's Treaty on June 24.
1795: In December of 1795 the Senate opened its legislative sessions to the public. The previous year, the Senate held its first public session to determine whether to seat Albert Gallatin, senator-elect from Pennsylvania, and voted to end the practice of holding legislative sessions behind closed doors.
1795: On December 15, John Rutledge became the first Supreme Court nominee to be rejected by the Senate .
1797: On March 25, the President exercised his right, for the first time, to call an "extraordinary session" of Congress.
1797: William Blount of Tennessee became the first senator to be expelled on July 8.
1798: The Senate convened its first impeachment trial -- of former Senator William Blount -- on December 17.
1800: The Senate took up residence in the north wing of the unfinished Capitol in Washington, D.C. on November 17, and achieved its first quorum in the new national capital on November 21.