Dating postcards often involves a little detective work. For instance, we can easily state that the postcard below was printed sometime after 1920, because it is of Meiji Shrine. Putting an upper bound on the year is more difficult: all we have to rely on are subtle hints like hairstyles, clothing, and columns of uniformed soldiers.

If you spend a little time looking through pre-war Tokyo postcards, you'll find that "troops marching through Meiji shrine" was a common theme -- probably because there was actually a barracks in the gaien area.

Here's another postcard with a completely different approach to the same visual theme. Notice how the straight, regular line of soldiers receding into the middle ground almost becomes an element in the park's design, on equal footing with the torii. (The size of the shrine area is also given, in tsubo.*)

With militarism snowballing too, you got soldiers in your Meiji Shrine photograph even when you weren't trying:

A few years later, the whole place burned to the ground.