Where Is the Hour Changed?
the hour would change for all points within that zone. Under this system all timepieces in any one zone point to the same hour. So the clock time changes only as you go east or west. All points on a north and south line have the same time as the zone in which it is located.
For convenience in adjusting the time in America the country was divided into four east and west zones. The first zone takes in everything on a straight north and south line east of Pittsburg, and is called Eastern time. The second zone extends from Pittsburg to Chicago, and is called Central time; the third zone extends from Chicago to Denver, and is called Mountain time; while the fourth zone extends from Denver to the Pacific Ocean. These selections were made because the sun actually rises about one hour later in Pittsburg than in New York; one hour later in Chicago than in Pittsburg; one hour later in Denver than in Chicago, and one hour later on the Pacific Coast than in Denver. Under this plan when it is nine o’clock in New York it is only eight o’clock at Pittsburg and all points in the Central zone; seven o’clock in all points in the Mountain zone; six o’clock in Denver and five o’clock in San Francisco. As you keep travelling westward you drop one hour of the clock time in every zone, and as under this system the earth’s east to west distance is divided into twenty-four such zones, if you went west entirely around the world you would lose a whole day of clock time.
If, however, you went around the world from west to east in the same manner you would gain a whole day.