[MathMonkeyMan]

Detroit is moving southwest along with the rest of the [North American tectonic plate][1]. It's not moving relative to surrounding cities, though.

[1]: https://en.wikipedia.org/wiki/North_American_plate#Plate_mot...

[saghm]

It's also moving through time at a rate of one second per second (but similarly not relative to the surrounding cities).

[MathMonkeyMan]

I was wondering about its reference frame as compared to surrounding cities, but I don't know if the difference could be measured. They are accelerating in different directions (towards the Earth, primarily).