United States Time Zone Map

On November 18th 1883 the Unites States of America was effectively divided into four specific time zones. The jurisdiction over these divided time zones was given to a regulatory agency in the United States known as the Interstate Commerce Commission.
The purpose of this particular agency was to effectively regulate railroads which also included trucking, to ensure competitive and reasonable rates by removing any instances of rate discrimination and ensure that all locations were observed as maintaining their respective local times within each time zone. Initially the divided zones within United States were created for the sole purpose of including four separate meridians without any consideration given to daylight saving time.
The four divided zones were observed as, The Eastern Standard Time, The Mountain Standard Time, The Pacific Standard Time and the Central Standard Time.

In 1967 the regulating responsibilities of the Interstate Commerce Commission through a congressional act were transferred to the United States Department of Transportation otherwise known as the DOT. Today the United States and its associated territories have successfully adopted a standard time existing throughout no more than nine time zones.
The time zones within the United States are adequately defined within the United States Code under Title 15 in Chapter 6 and in Subchapter 9 labeled Standard Time. The term associated with Coordinated Universal Time or UTC by United States laws governing time zones has been modified to reflect a meaning of the time scale respective to the General Conference of Weights and Measures for the purpose of the United States Naval Secretary and the Secretary of Commerce.
The Department of Transportation is charged with the additional responsibility of governing all rules maintained by Daylight Saving Time or DST transitions regardless of the fact that not all States are accustomed to observe instances of daylight saving time. The United States Energy Policy Act of 2005 under section 10 effectively states that States within the United States of America observing daylight saving time would begin this transition on the second day of the month of March and end on the first Sunday in the month of November.
This Energy Policy Act however does not place any limitations to the rights of those states and their adjoining territories such as Hawaii, Puerto Rico, Guam, the Virgin Islands and the majority of Arizona as well as a few others who have opt not to observe any instance of daylight saving time.
Daylight Savings Time commonly referred to as Summer Time by many Americans is observed as a means to make the most of the existing daylight in the evening time by advancing the clocks an hour ahead during the longer days experienced during the summer months and then back during the fall and winter months.
Most Americans are of the belief that the transition to daylight savings during these months could be the cause of fewer instances of road accidents and in addition will allow their children more interactive social times which will also enhance the commercial effect of tourism through increased time to accommodate outdoor activities.