Yes, most winter days near sunset, good numbers of those crows fly in from the east side of Denver (and beyond?). They often fly directly over my house just off East Colfax, about 4 miles east of the Capitol.
One recent evening I counted 805, another 529, all flying west to their winter night roosts.
Their flyovers coincide roughly with official sunset and go on 15-20 minutes.
I had been wondering where they were ending up.
Coincidentally, I was recycling last week through a pile of bird-related magazines and came upon a fascinating piece from a year or two ago about a massive winter roost in Lawrence, MA, with more than 15,000 American and Fish Crows nightly. They roost in various banks of trees around the area but also "stage" before the roosting in parking lots of former industrial mills, as well as on the frozen Merrimack River.
I can't find that article now, but a story in the local daily paper from the same time went into considerable detail:
Good winter birding,
Patrick O'Driscoll
Denver