According to this page, it's a sad tale of Maryland getting screwed over repeatedly over the course of a couple hundred years: http://blog.mailasail.com/vulcanspirit/220 Also this http://answers.yahoo.com/question/index?qid=20070615121704AA2i66m
It does have a strange shape, and the geography varies a great deal from one end to the coast. Partly, the shape is determined by the Potomac River; party by the Mason Dixon Line, partly by how Washington, DC is carved out of it. The western end is mountainous/Appalachian; then, gradually descending rolling hills on down to Baltimore, to where it become more flat to the south of the city, and going east, across the bay and to the shore, where there's a lot of marshes. It's got a lot of river valleys, all draining down into the Chesapeake, so even where it is relatively flat, these areas can be steep/hilly. So the odd shape also corresponds to a wide variety of plant life, and topography/micro-climates. I moved here from Michigan, and though it's much smaller, it's bigger than it looks.
US states having such straight borders is weird. The borders in Central Asia are amazing*: *nerdiest sentence I've ever written.
