You vote matters. Just only a little bit. Your individual vote wouldn't have changed the election. Does that mean you would assign someones vote as the "winner" that decided the election? No, your vote is part of the whole.

Go ahead and give yourself 1/80,000,000 th of the credit for a win.

As for the states you mentioned.

The governor. Or rather the "Governator" of California is a Republican. And Texas has been a major factor in the Dems nominating process.

So being the the party and voting can clearly matter. There are also ballot initiatives and a wide number of things.

Granted on specific vote for a president in the general election it is possible a vote doesn't really count due to the nature of states. Though at the least you actually make the other side expend the effort and resources to get that win. But you should be there to vote for other stuff anyway.