Final answer:
No states in the U.S. observe daylight saving time year-round; most observe it between April and October. Arizona and Hawaii do not participate in daylight saving time at all. The U.S. adopted standard time zones in 1883 to simplify time keeping across the nation.
Step-by-step explanation:
No states in the United States observe daylight saving time year-round. The purpose of daylight saving time is to shift the clock one hour forward between April and October to extend daylight into the evening hours. Most states participate in daylight saving time during these months but revert to standard time during the rest of the year.
In contrast, states like Arizona and Hawaii do not observe daylight saving time at all, opting instead to use standard time throughout the year. The concept of adjusting time schedules to make better use of daylight dates back to the 19th century when each community had its own local time. It was not until 1883 that the US adopted standard time zones to coordinate time more efficiently across the nation. Today, daylight saving time is still a matter of legislative debate in some areas, as it requires individuals and businesses to adjust their routines twice a year.