Arlington Memorial Bridge in Washington DC would be an outstanding example of this, and I’d wager the vast majority of local residents, even those who use the bridge every day, think they’re crossing from DC into Virginia, or vice versa, when they’re on the bridge. They’re not–the islands in the river are in the District of Columbia (or Maryland, depending on where the islands are), and the southern/western end of that bridge is on Columbia Island.
It doesn’t help that there are no signs marking where the line actually is.
NPS apparently
hates to sign political boundaries. Your example is a good one. There are no signs at all marking the D.C./Virginia border on the George Washington Memorial Parkway, nor on Washington Boulevard, S.W. nor on Memorial Avenue, S.W.
For some reason the Maryland/D.C. border is signed on Clara Barton Parkway, N.W. (example headed into Maryland
here).
Another example is on U.S. 50 on the east side of the District of Columbia. The border is at the east end of the bridge that carries U.S. 50 (New York Avenue, N.E.) over the Anacostia River, but the border just happens to cross the river near the DDOT-maintained bridge (map
here).
Because the Maryland approach to the bridge is National Park Service maintenance, there's no sign that mentions the D.C./Maryland border at all. The sign put up by D.C. is well beyond the bridge on the westbound side
here near the Costco store, and the one installed by Maryland is well after U.S. 50 becomes a state-maintained road
here. There is no sign at all on the Baltimore-Washington Parkway ("secret" MD-295).
On another NPS Parkway, the Blue Ridge Parkway, when I first drove it many years ago, there was no sign informing parkway users that they had crossed a state boundary. According to GSV there has been one since at least 2008 (when GSV last drove the parkway), headed north from N.C. to Va.
here and south from the Commonwealth into North Carolina
here.
IMO the style of these signs are appropriate for a national park, and would work well at the locations discussed above.