Railroad history digital collections. Links to 5 varied digital collections for railroads in the 19th and early 20th centuries, mainly in the U.S.
1. U.S. Railroad maps, 1828 to 1900
2. Railroad Periodicals; 19th Century through 1930. 90 titles
3. Railroad Transportation & Operations Online Book Collection at Century Past Library
4. California State Railroad Museum Library digital collection
5. The Transcontinental Railroad; history of railroad technology