Originally Railroads.
In the continental US, the four zones are Eastern, Central, Mountain and Pacific.
pacific, eastern, central, mountain
I'm thinkin' four
The railroads divided the US into four standard time zones to make their schedules more standard.
Canada has six time zones, while the contiguous United States has four time zones (Eastern, Central, Mountain, and Pacific).
There are several time zones in the continental US. Eastern, Central, Mountain, Arizona, Pacific, and Alaska.
Time zones were officially established in the US on November 18, 1883 by the railroads in order to standardize schedules. This was known as the Standard Time Act, which divided the US into four time zones: Eastern, Central, Mountain, and Pacific.
By introducing four standard time zones across the country.
The railroads divided the US into four standard time zones to make their schedules more standard.
The railroads
to make their schedules more standard
to make their schedules more standard