On July 23rd radio station Kool 107.9 FM Western Colorado's Greatest Hits, had a brief article listing the states where you can marry a cousin. Here is the introduction:
The phrase "keeping it in the family" can mean something a bit different in Colorado and 18 other states in the US as it is legal to marry your first cousin. Before the Civil War, marriage to a cousin was legal in all states according to Wikipedia.
We're not just talking about a second cousin removed by marriage either. Marrying your first cousin in Colorado is entirely legal in the state. Think of your mom's brother's kid. Yep, you could legally marry them in 19 states.