I am not 100% sure how voting in the US works, but I watched a documentary, where a voter ID is not required... Which means voting itself cannot be traced to remove duplicated results, or results by non-US citizens. Admittedly, it's a documentary I watched a long time ago, so I am not 100% aware of the current situation.

In my place, they just bring aliens and old people on busses to flood the votes. They also pay 50 bucks, if you're willing to sell your vote.

I agree with the title that elections are very easy to rig. I worked for a betting company, and while it seems that the bets are not rigged, the sport itself is very, very rigged. You'd be surprised that paying off only 2 players can result in the exact outcome you wanted. (That's for major sports, I don't know how all sports are rigged)

However, an important tool in rigging anything is convincing the audience that the major 2 contestants are very close to winning. This means the media is part of it. And if they are, they will bet for easy wins. And if you can monitor those bets, you'd know the outcome.

Elections are extremely easy to identify the winner in the US. Watch the latest movies, commercials, series, etc. about the latest political propaganda. Either they want change, or they want to keep the current situation. That's how you'd know the winner because in the US there are only 2 parties. That's similar everywhere because it works tho.