Final answer:
A significant population change in a state can alter its Electoral College votes since these are based on the state's number of congressional representatives, which are reassigned every ten years after the census.
Step-by-step explanation:
A significant change in a state's population, as determined by the national census taken every ten years, can alter the state's number of Electoral College votes. The national census counts the number of people in the United States and assesses where they live. This data is then used to reapportion the number of seats each state holds in the House of Representatives, which directly impacts the number of Electoral College votes a state receives, as this number is equal to the total number of senators and representatives in Congress attributed to that state.
When the population of a state increases or decreases substantially, it can gain or lose representatives in the House. Since the total number of House members is fixed at 435 due to the Permanent Apportionment Act of 1929, if one state gains a representative, another must lose one. Consequently, after each national census, states may experience a shift in their Electoral College representation, which can influence the outcome of presidential elections.