Well, there is a consideration related to the Electoral College that has led to the convention of choosing a running mate from a different state:

Article II, Section 1, Clause 3 of the U.S. Constitution, which outlines the original procedure for electing the President and Vice President. The Twelfth Amendment, ratified in 1804, modified this procedure but retained the rule that electors (members of the Electoral College) cannot vote for both a President and a Vice President from their own state:

"The Electors shall meet in their respective states and vote by ballot for President and Vice-President, one of whom, at least, shall not be an inhabitant of the same state with themselves."

So, that's where this comes from. The provision was designed to prevent electors from voting exclusively for candidates from their own state, which could lead to regionalism and weaken the unity of the country. In practice, this means that if the President and Vice President were both from the same state, the electors of that state would not be able to vote for both of them. This could potentially disadvantage the candidates in the electoral process.

Anyway, to avoid this issue presidential candidates typically choose a running mate from a different state. However, there is no explicit constitutional prohibition against the President and Vice President being residents of the same state.

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