John Tyler was pro tem in 1835.
Could you mean pro tempore or pro tem? Pro tem means "for the time being" or temporarily.
pro tem
pro tem
He is the president pro tem of the Senate, but can only vote to break a tie.
B. a president pro tem.
Barack O'bama
bunk nigs
The third person in line is the President Pro Tempore of the U.S. Senate, following the Vice President and Speaker of the House.
The president pro tem of the Senate.
Robert Byrd (D) West Virginia
The term "pro tem" means "for a time". The President Pro Tem of the US Senate takes over the chairmanship of the Senate when the Vice President, who normally serves as the President of the Senate (and yes, that is per ordinance of the US Constitution) cannot be present in the Senate during times when the Senate is in session. So it's safe to presume that if there was, anywhere, a "mayor pro tem", then that would mean a person filling in temporarily for a mayor who was not able to be present at that time.
The person that is known is the vice president.