In a perfect world, everyone would label their photographs with the names of the subjects, the date and the location the photo was taken, and what (if any) special occasion it was. However, we do not live in a perfect world. It's not unusual to come across old pictures in collections that had no identification at all. This can be a huge problem in genealogy. Thankfully, there are some methods you can use to help narrow the range when dating the photograph.
Identify the Photographer
In the past, most families did not own their own camera. Instead, they used a paid photographer. Check the front and back of the photograph to see if you can identify who took it. Once you have a name, see if you can track down where and when they were in business. You may even get lucky and find that the business is a family-owned one that is still in operation and has records of all photographs taken.
Look at Other Things in the Photo
Is there an automobile in the picture? If there is, try to identify it and then determine when it was first manufactured. For instance, if a picture has a Ford Model T in it, you know the picture was taken no earlier than 1908. Household appliances, the style of a house, farm equipment, televisions and telephones can also help you determine the year.
Look at Setting
Is it farm or city? If it is a farm and you know the couple only lived on a farm briefly, that narrows the gap. Is it possible that the tiny sapling in the front yard of the family homeplace is the same tree as the one that came down in the storm a week ago? Start counting rings and research how quickly that type of tree grows. Does it look like the area is in a drought? Look up historical weather for the area.
Check Out Their Fashion Sense
The type of clothing or hairstyle can go a long way in dating a photograph. Fashion trends change over the years, especially for women. Check out The Costume Page to see if you can narrow down the year that look was in fashion. Check your local library for copies of books on fashion through the years. Keep in mind that those living in extremely rural areas may not be as up to date on fashion as their city counterparts.
Determine the Photo Type
Is it a daguerreotype, ambrotype, tintype, carte de visite or a cabinet card? I found a great resource for determining the type of photograph. It also tells you when that type of photograph was popular as well as the approximate cost at the time.