I located a large number of these insulators on an abandoned rail line. I've not found them on the internet or my reference book. The state of Illinois is embossed with the number 119 inside the state and the number 30 on the left side. Any information would be appreciated. ***ANSWER:*** Information from Clint Gaylord and Joe Maurath, Jr. identified this as manufactured by Illinois Electric Porcelain Company. The 30 embossed to the left of the Illinois outline indicates it was made in 1930 and the 119 inside the state is the style number. Thanks for the help.