I don't know about any state, but I know about Florida. In Florida, you're entitled to half of the retirement that was earned during the marriage. So, for instance, if your husband spent 20 years earning his retirement, and you were married to your husband for the last 10 of those 20 years, you'd be entitled to 25% of the retirement. That is, you are married to him for half of the time he was earning his retirement, and you get half of the half, or 25%.
It can be a little more complicated than that. For instance, he may have been earning interest on the money he earned in the first half of gaining his retirement, and you wouldn't be entitled to that interest, or perhaps his retirement was in the stock market, where it lost a lot of money in the second half of his 20 years, therefore you get a lot less money. But, as a general rule, you get half of the retirement that's earned while you're married.