Edward Hopper, Early Sunday Morning, 1930

Carter Foster: A building very much like Early Sunday Morning forms the background of Nighthawks. Early Sunday Morning represents daytime. Nighthawks represents nighttime. 

Here, the overarching subject matter would be times of day and the passing of time, day to night. It's also about memory and the way that the urban environment changes. I think that we can look at the paintings together and they enrich each other and give us a larger context that Hopper was thinking about when he made both works.