RARE 1917 TEXAS ELECTRIC RAILWAY Dallas Tx Envelope to Sangamo Electric Co.

Description

1st - I AM NOT A BUSINESS AND DO NOT HAVE POSTAL PICK-UPS TWICE A DAY  so please allow me IF needed an extra day or 2 to get to the Post Office.
Sorry but sometimes, not always, the colors are off/yellowish when my is taking picts of bright things.
l acquired a small lot of RARE railroad/railway related envelopes from 1917 of mostly defunct railroads. I bought all of these envelopes because I know how rare and unusual they actually are and I'm sure there is someone out there that appreciates the rarity and collects anything related to the subject above.
Apparently someone back in 1917 that worked for Sangamo Electric Co. of Springfield Illinois thought enough of rail transportation that they saved any envelopes related?
They will know that they will probably never see something like this again and as these items get older, most will be tossed, some will just rot away and fewer and fewer will come to market and will be scarffed up right away.
PLEASE ask questions and do your research before you bid and BE SURE it is what you want so we don't have to go through the hassles and costs of returning. Thank you.