Serial killers and famous murderers have existed almost as long as mankind, we're sure.

But as in so many things, the United States may just have perfected the thing. Each state has its own infamous episode, some very well-known, others obscure.

Three things we learned while putting together this United States of Murder map:

3. Serial killer aficionados look down their noses at what they call "spree killers" We contacted some serial-killer buffs we knew for suggestions, and listed examples of what we had come up with so far. To a man (and they were all men), they felt the need to point out that someone like Charles Whitman was a "spree killer," and should not really be lumped in with such fascinating characters as Ted Bundy. Apparently efficiently doing all your killing in one episode is frowned upon.

2. Some states offer a cornucopia of choices; some not You want a wide range of options to pick from? Try California. They grow serial killers out there on trees. Very deadly, cunning, elusive trees. You want to find a famous murder in North Dakota or Kentucky? Good luck with that.

1. It's not about the numbers Yeah, yeah, we know: Juan Corona's not the California candidate. Henry Lee Lucas didn't make it anywhere. That's because we didn't choose on the unthinking basis of sheer productivity; we took into account notoriety, sometimes style, or -- in the case of, say, Vermont -- sheer gratitude that there was something to list.

Disagree with any of the choices? Let us know.

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