How come presidents only get to run to terms

Franklin Delano Roosevelt, the Democratic president that led the US to victory in the Second World War, won four consecutive terms as president. He served 3 full terms and died in the beginning of his fourth term. After the death of FDR, a limit of two consecutive terms was fixed for Americans presidents when Congress passed the 22nd Amendment.

Explanation:

a reason that was key to coolidge's victory in the 1924 presidental election was that; democratic party supporters were split in the north and south.