How old was Abraham Lincoln when he was first elected to public office? July 13, 2020 by Pamela Landy Abraham Lincoln was 25 when he was elected to the Illinois state legislature as an assemblyman in 1834. Related Answers What was a summoner or A canon’s yeoman or A franklin or A manciple or a reeve? When did Spiro Agnew resign from the vice-presidency? What play was President Abraham Lincoln watching at Ford’s Theater when he was assassinated? How many times did Raymond Massey play Abraham Lincoln? Did Abraham Lincoln write the Gettysburg Address on the back of an envelope? Where was President Abraham Lincoln born?