Final answer:
The majority of states in the U.S. use a winner-takes-all system where the Presidential candidate with the most votes in the state wins all of its electoral votes, except Maine and Nebraska which use a proportional system based on congressional districts.
Step-by-step explanation:
In a Presidential race, the way states apportion their electoral votes among the candidates is primarily through a winner-takes-all system. This means that the candidate with the majority of votes in a state receives all of the state's electoral votes. There are two exceptions to this rule: Maine and Nebraska, which use a congressional district method. In these states, electoral votes are allocated proportionally, with one electoral vote going to the popular vote winner in each congressional district, and two additional votes going to the state's overall popular vote winner.