This is the legal status of capital punishment in the different states of the U.S.:
(source, an interactive version of this map is here, where you can also see the method of execution and the date of the last execution for individual states)
Here’s the actual practice, including the numbers:
Here’s another version just showing the numbers of executions since 1976:
However, it’s better to look at the numbers execution per population (per million in this case):
And these are the numbers for the whole of U.S. history:
Update April 2012: Connecticut has now passed a repeal bill and jas become the 17th state to abolish capital punishment. Here’s an updated map:
About the methods of execution, there’s another map here. And another one here giving the numbers of executions by state. And, finally, there’s a map here showing which states allow the execution of juveniles.