In recent months, I have been directed toward three websites that display color photos from the first two decades of the 20th century. While my knowledge of photographic methods is limited at best, it seems that the color is imparted using different methods that were just being developed. I was so excited to find these, because the color photos make the lives of people about 100 years ago seem much more real. I thought I would share them to those who might find them useful as teaching aids or for research.
Autochromes de la Guerre
This site is in French, and shows photos using a method developed in 1903. These are pictures of soldiers from World War I, taken by war photographers. Even if you don't read French (mine is very rusty) you can still poke around on the site: there's a thumbnail on the right-hand margin that will pull up a little 10-photo slideshow.
The Great War in Color
This site is a great introduction to some very stunning photos and descriptions of different photographic processes. The definitions are easy to understand, and several important people in the development of color photographic methods are introduced. Several collections of color and black-and-white photos from World War I appear along the left-hand side ("Kid Soldiers of the Great War" is especially haunting), and some historical information as well (see "Adolf Hitler and Remarque in No Man's Land").
Russia in Color, A Century Ago
This site shows photos taken around Russia in 1909 and 1910. The color in the pictures is crisp and spectacular, and it looks like they could have been taken with a modern camera. What is especially useful for teachers (or even just interested viewers) is the Google maps below some of the images that allow you to visually reference the location where the picture was taken.
Captured: America in Color from 1939-1943
These pictures come from a bit later on, but I've included the link because they show pictures of everyday life in the U.S. I was especially struck by the images of rural America, and it was powerful to see color images of the sometimes cramped living quarters, but also to see street scenes and social activities.