What People Wore , by Douglas Gorsline, provides a visual history of dress from ancient times to the early 20th Century. His book is especially helpful in identifying pictures taken between 1900 and 1925. There were drastic changes in American women's fashions between 1905 and 1918. Check at your local library for Gorsline book and others on costumes, and how to identify photographs. Don't let that happen to your family's photographs.
Genealogists are as guilty as others in failing to identify and catalog family photographs.
And when we die our descendants are left with pictures of strange people and unknown places. Consequently, they are discarded and lost to later generations.