1. Time Zone Maps Day 13

2. Early Timekeeping Before the invention of clocks, people marked the time of day using the sun. Many used a sundial to tell what time it was. The sun is not at the same place in the sky at various locations around the world at the same time, so a sundial was not really practical.

3. When well-regulated mechanical clocks became widespread in the early 19th century each city began to use some form of solar time on which to base clock settings. Solar time still meant that time differed from place to place. In 1675, Greenwich Mean Time (GMT) was established at the Royal Observatory in England to aid English sailors in planning sea travel and routes. It also provided a standard reference time for all of the cities in England which, up until them, each had a different local time. Greenwich Mean Time

4. Local “solar” time became even less reliable when railroads and telecommunications improved—clocks were set at different times from one place to the next. The use of time zones smoothed out these differences. The first time zone in the world was established in Great Britain using GMT. This quickly became known as Railway Time. In 1852, the Royal Observatory in Greenwich began to transmit the first “time” signals so that clocks could all be set to the same time (synchronized). How Time Zones Came About

5. Timekeeping on by American railroads in the mid-19th century was somewhat confused. Each railroad company used its own standard time, usually based on the local time of its headquarters or most important train station. Some major railroad junctions (place where two or more railroad routes crossed) were served by several different railroad companies. In which case, the trainmaster had a separate clock for each railroad company. Very confusing!!!!! The main station in Pittsburgh, Pennsylvania had SIX different clocks to watch for the six different railroad companies that used its station. America’s Time Zones

6. By the 1880s, railroads in the U.S. and Canada agreed on time zones that were one hour apart. It was inaugurated on Sunday, November 18, 1883, also called "The Day of Two Noons", [4] when each railroad station clock was reset as standard-time noon was reached within each time zone. [4] Within one year, 85% of all cities with populations over 10,000, about 200 cities, were using standard time. By 1918, the U.S. Congress passed the Standard Time Act and it brought the confusion of times to an end when all regions of the U.S. were part of one of the established time zones. Time Zones Become Official

7. Time Zones A time zone is a region on Earth which has a consistent, legally authorized standard time throughout that region.

8. The U.S. now has 9 standard time zones. The Continental United States has 4. From east to west they are Eastern Standard Time, Central Standard Time, Mountain Standard Time, Pacific Standard Time.

9. As you move from East to West through the time zones, the time changes by one hour. When it is 8 a.m. in New York, for example, it is 7 a.m. in New Orleans, 6 a.m. in Denver, and 5 a.m. in Los Angeles.

11. http://www.timeanddate.com/worldclock/converter.html Use the time zone converter below to see what time it is in various cities around the world. Enter the current time for Shreveport. Select a city…..like Tokyo, Japan See the time difference between the two. Check out the date too. It may already be tomorrow in some locations!!!!