I've seen a few people do this; I don't recall who I saw do it first, or which time I decided to try it myself.
The orange states are the ones I don't remember having been
to (though I suppose I should ask my mother whether there
are any I've forgotten childhood trips to). I'm not absolutely
certain which side of the NH/ME border the place two NH friends
and I went to for dinner one time was, but I'm pretty sure it was
in NH. So far all of the states I consider myself to have
"properly visited", I've stayed overnight (or longer) in; I
did spend the night in a hotel in the middle of TN, but it was
just a sleep break en route to TX, and I didn't visit anyone or
stick around to see the sights, so I'm counting that as "drove
through (with an asterisk)". I've spent fifteen minutes in WA
when flight to Portland touched down in Seattle to let a few
people off, but if I can come up with the money to do so, I'm
hoping to attend a friend's wedding there this winter (prospects
are currently rather iffy but I've not yet given up hope). And
I've been camping in MD, VA, NC, NY, and (if Pennsic counts as
camping) PA. (Pennsic is more like living in a temporary
city, than "camping", but hey, I sleep in a tent there and have
cooked over a wood fire...) And no, I've not been to HI or AK
yet.. But I was tempted to add Canadian provinces I've visited.
And it only occurred to me half an hour ago that I should've picked colours to be distinct on a greyscale monitor, but I'm not wrestling with Photoshop all over again now.
If anyone can't see the PNG GIF file, let me know and I'll try
to make a GIF save properly. (For some reason the key kept
getting cut off when I tried to save as GIF.) (EDIT 20030713.1200:
since I got a complaint about the PNG, I tried again with the GIF.
Let's see whether I finally got the GIF to work correctly.)
Not, I think, a terribly impressive list of states, all told. Especially after subtracting the states I've merely driven through at high speed. But it does look more impressive this way than if I were to only colour in, say, the individual counties I've visited -- some of the states I've been to, I've only seen narrow slices of.