Model T Halftrack, 1920

Shorpy

This is 1920, and that looks like Key Bridge over the Potomac, which I cross every day, but in fact that's the Taft Bridge in the background. The Taft Bridge was finished in 1907 and has six small arches in the middle of each big one, while Key has eight, and carries Connecticut Avenue over Rock Creek. Key Bridge was not completed until 1923.

Hard to know who these people are, but the third person from the left appears to be General Black Jack Pershing (notice the stars on sleeve if you enlarge).

The Model T here has a different halftrack setup than I have seen before, with four tires on a side rather than the more customary three. This was called the Chase Track System.

The tank behind the Model T halftrack is a Mark VIII - a joint UK and US main battle tank for the 1919 western front offensive, which never occurred since Germany collapsed in November of 1918. After the World War I, 100 of these Mark VIII tanks were assembled in the US and used by the Army until they were mothballed in 1932. At the start of World War II, the tanks were given to Canada for training purposes.