According to the twenty-second amendment to the United States Constitution:
No person shall be elected to the office of the President more than twice.
This amendment was ratified in 1951, and Franklin D. Roosevelt was elected more than twice because this amendment wasn't still there.
I want to know:
Was there any limit on the number of times a person could have been elected the president of the United States before 1951?
If there was no limit, how come no one was elected more than twice before 1940s.