Provisions for absentee voting were made for early American colonists who were traveling or otherwise unable to get to the polls on Election Day even before the U.S. became the U.S.
According to Spencer Albright of the University of Richmond,
“In the United States absentee ballots were used in colonial times as early as the 17th century.”
BONUS QUESTION:
Who was the first American to vote for President from space?
ANSWER:
Leroy Chiao, Ph. D., Commander and NASA Science Officer
of the 10th mission to the International Space Station