The Library of Congress, one of the largest libraries in the world, not only contains writings, but also over 14 million photographs.
These have been purchased and archived since the mid-19th century.
About a million of these images have already been digitized, others exist as prints and negatives on some historical image carriers.
For years, the library has been publishing selected images via digital channels such as flickr and Instagram and making them freely available to the public.
She expressly requests that the pictures be commented on and missing information added, as many pictures arrived at the library with little or no labelling.
Christina Klein
picture editor
Follow I follow
One of the digitally published archives is the "Charles Milton Bell Collection", the life's work of a photographer who ran a photo studio in Washington DC at the end of the 19th century and over the years produced thousands of portraits of the city's residents.
Bell, who came from a family of photographers, opened his studio in 1873. Everyone came to see him: presidents and senators, merchants, church officials, the black and white middle class, Native Americans, children, the elderly, athletes, and quite a few pets.
The pictures are staged, partly in front of monochrome backgrounds, partly with props, partly in front of painted panoramas.
They are a document of the fashion of the time, provide information about social conditions, show values and individual characters.
Very little is known about the people depicted, sometimes only one name is handwritten on the pictures.
It is not always clear who added this information and when.
After Bell's death in 1893, his successors continued to run the studio in his name for over 20 years.
Over time, thousands of pictures were created in Studio Bell, which are of particular interest to genealogists today.
Entire families have been documented at Bell over decades and generations.
The Library of Congress, which acquired part of the collection in 1975, has now digitized and published 25,000 of the glass plate negatives.
CM Bell Collection
Copyright-free images from the Library of Congress