(4/26/06 9:39 am)
My understanding is that 1923 is the cut off date for copyrights here in the U.S.. Any image made prior to 1923 is copyright free. Images made in 1923 or later have a copyright of the life of the artist + 50 years. (I think it's 50, it might be 70.)
If you are using imagery just for, say, a postcard to send out that probably won't be a problem. If you are making copies of a picture to sell, then you should probably look to make sure their are no copyright holders, even for older images.