apropos of... interesting

From False Economy by Alan Beattie. (Chapter 7)

The telegraph and railroad developed together, the lines running alongside one another. In 1849, the New York and Erie Rail Road pioneered the use of the telegraph to control running operations. Five years later it was standard practice among the railroad companies.

These twin technologies, incidentally, helped establish their own standardization, including one of the most fundamental of all measurements: time. In the mid-nineteenth century there were more than two hundred different local times in the United States. Towns might be only a few minutes ahead or behind the time in the next town along. Even the American railroad companies used a total of some eighty different times, since journeys took so long that there was plenty of opportunity for people to change their watches. As railroad travel quickened and expanded, the potential for confusion multiplied, and in 1883 the railroads imposed a uniform system of time, with the four time zones that persist today: Eastern, Central, Mountain, and Pacific.

The railroads imposed it.