United States presidential line of succession
The laws about succession (after the vice president) were first created in 1792. The second in line, after the vice president was the leader of the Senate.  The next in line was the speaker of the House of Representatives.  In 1868, during the impeachment trial of President Andrew Johnson, Benjamin Wade was the leader of the Senate. He almost became president, but Johnson was found not guilty by one vote. Johnson had been the vice president for Abraham Lincoln. He became president after the assassination of Lincoln. Because of Lincoln's assassination, there was no vice president at the time.