September 24, 2019 - A formal impeachment investigation into Trump is announced by House Speaker Nancy Pelosi.
October 31, 2019 - A resolution to formalize the procedures of the impeachment investigation against Trump is approved by the House.
November 13, 2019 - The investigation's first public hearings will take place.
December 10, 2019 - House Democratic leaders announce that they will bring two impeachment articles against Trump, accusing him of abuse of power and obstruction of Congress.
December 13, 2019 - In a party-line vote, the House Judiciary Committee endorses the two articles of impeachment, setting the stage for a vote on the House floor.
December 18, 2019 - To impeach Trump, the House votes nearly exclusively along party lines. The vote for misuse of authority is 230-197 and the Congressional vote for obstruction is 229-198.
January 16, 2020 - Upon voting to approve the seven supervisors who will prosecute the lawsuit, the House officially sends two articles of impeachment to the Senate.
January 16, 2020 - A non-partisan congressional watchdog, the Government Accountability Office, claims the Trump administration broke the rules when it denied Congress-appropriated US defense assistance to Ukraine in 2019.
January 16, 2020 - Formally, the Senate impeachment hearing begins. Chief Justice John Roberts of the Supreme Court swears in the senators. On the floor of the Senate, each new member of the chamber comes forward and signs the oath book.
February 5, 2020 - To acquit Trump, the Senate meets. Sen. Mitt Romney is the only Republican to vote to prosecute the President on the misuse of power allegation, voting in a 52-48 non-guilty vote with all Senate Democrats. Romney votes against the obstruction of Congress allegation, which breaks into straight party lines, with Republicans, 53-47 for acquittal.
13 January 2021 - After the January 6 Capitol protests, the House votes to impeach Trump for a second time, 232-197, on charges of inciting an uprising. Trump is expected to end his term (with just a week left) when it takes a Senate conviction, even though he's been impeached, to oust him.
February 13, 2021 - In its second impeachment trial, the Senate acquits former President Trump, voting that Trump is not guilty of inciting the deadly riot at the US Capitol on January 6—but the verdict amounts to a bipartisan rebuke of the former president, with seven Republicans finding him guilty, with a final vote of 57 guilty to 43 not guilty.