Because people used to depend on the position of the sun to determine local time, traveling by train from east to west (or vice versa) in the United States necessitated adjusting a watch by one minute every 12 miles. Individual cities had different time standards, wreaking havoc on train schedules. The adoption of time zones in 1883 solved this problem.
The Central Time Zone is the second of the U.S. zones going from east to west and covers such states as Illinois, Mississippi and part of Texas. To determine Standard Time in this zone, subtract six hours from Universal Time, Coordinated (UTC). To determine Daylight Savings Time, subtract five hours from UTC.
The Pacific Time Zone is the westernmost of the continental U.S. zones and covers California, Washington and parts of Oregon, Nevada and Idaho. Standard time in this zone is eight hours behind UTC and Daylight Time is seven hours behind it.
Pacific Time also covers parts of Canada and Mexico, as well as to Belize, Guatemala, Honduras, El Salvador, Nicaragua and Costa Rica; the Galapagos in Ecuador; and Easter Island in Chile.
Though most states fall entirely within a specific time zone, a few states fall into two time zones. This split occurs in Oregon, Nevada and Idaho in the Pacific Time Zone, and in 10 states in the Central Time Zone including Florida, Michigan and Texas.
Although Arizona is located in the Mountain Time Zone, it does not observe Daylight Saving Time (DST) except in the Navajo Nation. Thus, during DST for the United States, Arizona observes Pacific Daylight Time.
