I had a look around to see if anyone mentioned it, couldn't find an earlier post.
In reality, flights to and from DCA are restricted to cities up to 1,250 miles/2010 km away. However, there are exemptions given to airlines to allow them to operate (a limited number of) routes beyond that limit.
I'm wondering whether there has been any discussion about introducing this feature in future updates. It would be great to go DCA-LAX or -SJU or even -LHR.