These are Square Indent Nails, some of them are marked "Unknown". If you have any information on those nails, or find a discrepancy, please E-Mail me.

Aigista-Aiken Railway	Benton Harbor, MI	Unknown	Indiana General Service Used in 1929	Indiana General Service Used in 1929
Indiana-Michigan Electric	Indiana-Michigan Electric	Iowa Public Service Charles City, Iowa	Benton Harbor, MI	Ohio Power Company
Pennsylvania Power & Light	Arizona	Public Service Power & Light, NJ	Salt Lake County Utah	Santa Fe RR "Steam Treated"
Unknown	Grand Junction Colorado Area	Union Electric      St. Louis, MO Area	Unknown