In 1940, people driving automobiles in Texas were not allowed to go faster than 45 M.P.H. According to the sign in the photo, light trucks and motor busses had to abide by a 40 M.P.H speed limit and heavy trucks had to stay under 25 MPH.
I must admit, I'd be thrilled if this were still the case today. I'm quite the nervous-nelly when it comes to keeping up with the speed of today's traffic.
I can't imagine it would go over well with the folks if they tried to impose these laws now, though. Plus, with all the traffic these days, we wouldn't be able to get anywhere in a timely manner.