[jfengel]

Virginia wanted to grow its exurbs, and Maryland didn't. Virginia created a lot of large houses on former farmland, where Maryland preserved more of it.

Maryland also did a better job of spreading out its employers. A lot of those Virginia exurbs still commute into DC, or at least Northern Virginia, making traffic a nightmare, at least during rush hour.

Another thing that slightly confuses that map: Virginia has much better arteries into DC. You get into DC from the south on I-395 and I-66, and they take you all the way downtown. Maryland has only surface streets. (It was supposed to have I-95 connecting straight through the city to join up with I-395, and I-595 where New York Avenue is, but that would have destroyed a lot of neighborhoods in exactly the way they were destroyed in building 66 and 395.)

That means that there's a fair bit of Virginia that is technically 45 minutes away from the center of the city, but not during rush hour. The 45 minute line in Maryland is pretty close in, but the 1 hour line turns out to be quite broad, because you can reach it on Maryland's interstates that flow pretty freely (parts of it, even during rush hour).

Of course you really should be taking public transport, except during a pandemic. The driving and parking are both horrible.