On the morning after moving into the new house in McKees Rocks, I woke up in my new bedroom. It was dark, and I found myself wondering what time it was (since I had yet to uncrate my digital alarm clock with the glowing red numbers). I fumbled around, found my wristwatch (us old people still use wristwatches instead of just looking at our cell phones), and lit up the display. It was 7am. I thought to myself: how can it be seven o'clock? It's still dark out!
I was face to face with one of the side effects of standardized time zones. Two hundred years ago, every city kept its own time, setting noon when the sun was directly overhead. However, after railroads became commonplace, it was necessary for large areas to all keep to the same time. Eventually, Congress adopted the Standard Time Act in 1918, creating the four current times zones of the Lower 48 States.
Back in Newport, near the eastern edge of the Eastern Time Zone, the sun was usually up by quittin' time, 7am. Even on the day of the Winter Soltice, the sun might not be up, but it was bright enough that I could drive home without using my headlights.
Then, that October morning, I woke up in McKees Rocks, 550 miles and nine degrees longitude west of Newport, but still in the Eastern Time Zone. The sun that was rising even then over the golden dome of Newport City Hall wouldn't be lighting up McKees Rocks for another thirty minutes. In McKees Rocks, it was still dark out.
And of course, to a hypothetical inhabitant of, say, Ann Arbor, Michigan, 200 miles and 3.5 degrees longitude further west, but still in the Eastern Time Zone, the effect would be even more pronounced. It would take the Earth fifty minutes to rotate our hypothetical Michiganian around to the terminator after Newport had passed through. If she traveled to Newport, our hypothetical Michiganian would wake to find sunlight pouring through her bedroom window, then would glance at the bedside clock and think in astonishment: how can it be light out? It's only seven o'clock!