Okay kiddo, so you know how in school you have friends you play with and sometimes you work together on projects? Well, grown-ups also have groups they belong to, called political parties. These groups have their own ideas about how the country should be run so they work together to help get people elected who agree with their ideas.
Now, different states in the U.S.A. have different amounts of people who belong to each political party. Some states have more people who belong to one party than the other, and some have a balance of both. Think of it like how some classrooms have more girls and some have more boys.
When people go to vote in elections, they usually vote for the candidate who belongs to the same party as them. So if there are a lot of people in a state who belong to one party, then that party will have a better chance of winning the election in that state.
But, it's important to remember that just because a state has more people who belong to one party, that doesn't mean everyone in the state belongs to that party. There are always people who belong to the other party or who don't belong to any party at all.
So, that's how political party strength works in U.S. states. It's just like having more friends who like the same games you do - you have a better chance of playing those games more often!