An incredible amount of information is online now, and by that I mean basically all of it. Search for a minute order number, and it pops up. The link is for minute order 016701, the general re-description of the highway system in 1939 that I've always wanted to see. I'm linking to that results page because I can't find the main search page. It opens the minutes, in which the minute orders are included. The individual order numbers are on the left of each page. 016701 is in the first file listed, Sep. 25, 1939. I'm linking to that results page because I can't find the main search page, and that's the minute order I most wanted to see. I could spend months doing nothing else.
http://publiccm.txdot.gov/minord/mosearch/Pages/Minute-Order-Search-Results.aspx#k=016701
NE2 is going through the early minute orders and listing them with descriptions of their highway designations. I was most interested in the general redescription in 1939, but it's really neat to have the earlier descriptions.
http://en.wikipedia.org/wiki/User:NE2/TX_minute_orders (http://en.wikipedia.org/wiki/User:NE2/TX_minute_orders)
The meat of what I'm compiling is on the talk page: http://en.wikipedia.org/wiki/User_talk:NE2/TX_minute_orders
Unfortunately there seem to be a number of omissions from the early minutes. Sometimes they realized and retroactively made the changes, but not usually.