Comparing two views is an invitation to slow down. A roofline, curb, sign, or tree can make a street recognizable even when its uses have changed.
Begin with an identifiable view
The Pomona Public Library Digital Collections are a starting point for finding documented images. Record the collection, item identifier, caption, and date information before interpreting a photograph. An estimated date should remain an estimate.
Match the viewpoint
Use a safe, publicly accessible position for a new photograph. Record its date and explain any difference in angle or framing. Buildings can appear to move when the photographer has simply stood somewhere else.
Separate observation from interpretation
A missing doorway is an observation. The reason it disappeared needs further evidence. Check directories, maps, planning records, and other photographs before turning a visible change into a historical claim.
About the demonstration images
The comparison images in this demo are generated illustrations. They are not a verified before-and-after pair, and they do not establish the appearance of a specific street at a particular date. Replace them with appropriately documented images when publishing a historical comparison.