A Pomona then and now comparison can begin with a familiar surprise: the corner still looks recognizable, but almost everything around it has changed. A roofline survives above new storefronts. A tree hides a former entrance. A wide street occupies space that once looked intimate. The most useful comparisons go beyond spotting differences. They ask how the pictures were made, what each image can establish, and which parts of the story require other evidence.
Start with an image you can identify
Choose a photograph with enough information to investigate: a street, building, intersection, business name, or recognizable landmark. The Pomona Public Library Digital Collections provide one place to begin searching. Save the item’s catalog information alongside your notes. A downloaded image without its title, collection, identifier, and source link soon becomes difficult to check or share responsibly.
Read captions critically. The Library of Congress guidance on photographic evidence treats the image and its accompanying description as material to evaluate. A caption may have been written long after the photograph. A familiar building name may refer to an earlier occupant, while an approximate date may reflect cataloging judgment rather than a dated negative.
Separate the photograph’s date from its subject
A building completed in one year could be photographed decades later. Likewise, the date on a postcard may concern mailing, printing, or publication. Record exactly what the available date describes. If the collection supplies only a range, preserve that range. Precision is useful only when the evidence supports it; an honest “circa” is better than a guessed year presented as fact.
Give each working image a short source note before heading outside. Include the direction you think the camera faced, the features you expect to find, and any reasons the location remains uncertain. Bring a wider reference view if one exists. A close crop may show a beautiful doorway while removing the neighboring building that would confirm the address. This preparation turns a walk into a specific search and helps you recognize when a promising match is only a resemblance.
Match the viewpoint before comparing details
Find two or three relatively stable features, such as a corner, roofline, and distant structure. Use them together to estimate where the earlier camera stood. One feature alone can mislead, particularly when a street bends or several buildings repeat a similar design. Stand somewhere safe and publicly accessible. An approximate match from the sidewalk is preferable to stepping into traffic for a more dramatic composition.
Compare camera height and direction as well as location. A photograph taken from an upper window compresses the scene differently from an eye-level view. A wide-angle lens exaggerates nearby objects, while a longer lens can make distant features appear closer together. These differences may explain an apparent change in scale without any physical alteration to the street.
Notice what the frame leaves out
A photograph is a selected view. The camera might exclude an industrial yard, a neighboring house, or the crowd behind the photographer. Cropping can remove useful clues, and seasonal foliage can conceal a facade. When preparing a comparison, retain an uncropped reference copy. Explain any substantial crop so readers understand why a landmark visible in the source is missing from your presentation.
Use three separate notes: seen, inferred, unknown
“Three upper windows are visible” is an observation. “The upper floor may have been altered” is an inference. “The alteration date is unknown” states a limit. Keeping these categories separate prevents a plausible story from hardening into an unsupported claim. The Library of Congress primary source guides offer a useful framework of observation, reflection, and questioning.
Check the pictures against another kind of record
Once you have a visual question, choose a source that could answer it. A street directory may help identify a business at an address. A dated newspaper notice may establish a public opening. A building record may describe an alteration. None should be treated as a universal answer: a business opening does not necessarily date the building, and an address can survive a replacement structure.
Maps are especially helpful when the street itself has changed. The Library of Congress guide to interpreting Sanborn maps explains why the map’s key and conventions matter. Read the relevant edition carefully instead of assigning meanings to colors from memory. Our guide to researching a Pomona street develops this work into a fuller neighborhood investigation.
Let an unanswered question guide the next search
If local searching stalls, try a regional archive such as Cal Poly Pomona’s Pomona Valley Historical Collection. Search neighboring landmarks and former business names as well as the current address. A related view may resolve the orientation of your image even if it does not show the main subject directly.
Build a caption that carries the evidence
A good caption identifies the place, explains the dates, names the source, and distinguishes change from uncertainty. Begin with what both pictures clearly show. Then explain one or two meaningful differences. Close with any limitation that affects interpretation. This compact structure helps a reader understand the comparison without needing to reconstruct your entire research process.
For example, a hypothetical caption might say: “The earlier view shows an open porch; the present view shows an enclosed front room. The image dates establish that the enclosure occurred between these views, but the construction year remains unverified.” This is an example of method, not a claim about a particular Pomona property.
Look for continuity as carefully as change
Then-and-now projects often emphasize demolition or dramatic transformation. Look also for durable patterns: the same corner gathering people, a familiar route through a block, or a building continuing to support changing businesses. Our article on reading historic homes offers another way to notice continuity in ordinary streets. Survival can involve adaptation rather than an untouched appearance.
Be cautious when describing activity from one instant. An empty sidewalk does not prove that a district was deserted, just as a crowded event photograph does not establish everyday conditions. Time of day, weather, and the photographer’s purpose may account for the difference. A series of views offers a stronger basis for discussing patterns than a single dramatic pair.
Keep documentary photographs and illustrations distinct
An AI-generated historical scene cannot prove how Pomona looked. Neither can a reconstruction establish details missing from an original photograph. Label illustrative images clearly, and do not pair them with a current photograph as if they were authentic archival evidence. If you adjust a documentary image, retain its original file and explain changes that affect interpretation.
Before sharing archival material, check the collection’s reproduction and rights information. The Library of Congress house-history photograph guide can suggest further places to search. Bring your finished comparison back to our Then & Now collection with clear sources and modest claims. A careful comparison makes the city more legible while leaving room for the next discovery.
Image note: All three images are AI-generated illustrations, not archival photographs or verified views of specific Pomona sites.