I'm sure there's a handy Wikipedia article about this, but in a nutshell, no: they wanted the capital to be independent of states, but no state wanted to just give up all that land. So they came up with the idea of both MD and VA contributing land on either side of the river. This land was also basically a swamp, so it wasn't terribly valuable. The original city was a perfect square, 10 miles on each side (not aligned NSEW, however), and there were boundary stones at the 4 corners and one stone every mile along the border. These stones are mostly still there, though some of them are on private property so are inaccessible.
Anyway, for whatever reasons I forget now, DC decided in the 1800s to give the VA side back to the state of VA. What's left is the part MD donated, which is why DC looks so odd on a map: 3 sides are straight (one of them being 10 miles long, the others roughly half), and the 4th side is just the river.
Also, just look at a map: the border between VA and MD is the Potomac River itself. For some strange reason, the King of England set the boundary between the two states to be at the shoreline on the VA side, so the river belongs to MD. So if you're standing on the shore on the VA side and walk into the river, you're now in the state of MD.
> Anyway, for whatever reasons I forget now, DC decided in the 1800s to give the VA side back to the state of VA.
As seems to be the dominant theme of the 1800s in the U.S, the answer is slavery. Thanks, I hadn’t heard about this.
> In the 1830s, the district's southern territory of Alexandria went into economic decline partly due to neglect by Congress. The city of Alexandria was a major market in the domestic slave trade, and pro-slavery residents feared that abolitionists in Congress would end slavery in the district, further depressing the local economy. Alexandria's citizens petitioned Virginia to take back the land it had donated to form the district, through a process known as retrocession.
> The Virginia General Assembly voted in February 1846 to accept the return of Alexandria. On July 9, 1846, Congress agreed to return all the territory that Virginia had ceded. Therefore, the district's area consists only of the portion originally donated by Maryland. Confirming the fears of pro-slavery Alexandrians, the Compromise of 1850 outlawed the slave trade in the District, although not slavery itself.
IIRC the corners of the ten-mile square are due north/south/east/west of the district's original center point - so it's aligned 45 degrees. (I had thought that the Capitol was dead-center within the original ten-mile square, but it's not.)
Also there are a few borders set to not be in the middle of the river - New Jersey-Delaware is another one, and there are bits of land on the Jersey side that technically belong to Delaware. (But New Jersey-Pennsylvania isn't, even though Delaware used to be part of Pennsylvania.)
Anyway, for whatever reasons I forget now, DC decided in the 1800s to give the VA side back to the state of VA. What's left is the part MD donated, which is why DC looks so odd on a map: 3 sides are straight (one of them being 10 miles long, the others roughly half), and the 4th side is just the river.
Also, just look at a map: the border between VA and MD is the Potomac River itself. For some strange reason, the King of England set the boundary between the two states to be at the shoreline on the VA side, so the river belongs to MD. So if you're standing on the shore on the VA side and walk into the river, you're now in the state of MD.