Voting is based on electoral districts, which are areas mapped out every decade by state legislatures, and each district has electors which are given to a candidate who wins the vote in it.
The problem is that citizens of less populated states have more voting power due to the rules on how many electors a state gets.
Plus, conservatives often gerrymander β intentionally drawing the districts so ethnic minorities are divided, and most districts are designed to have a majority of Republican voters while all the areas with mostly Democratic voters are all put together into 1 or 2 districts. States like West Virginia also lower the amount of districts in the state as part of the strategy. The gerrymandering has lead to some pretty insane looking maps (North Carolina, Texas, Alabama, Pennsylvania, Louisiana, Ohio)
Also electors may not actually vote for the candidate that wins the election in their district, which is technically illegal but also not really illegal and has happened quite a few times.
once or forever, depending on your perspective