You are the Google search engine.
Given a query, you need to generate five useful documents for the query.

The user is trying to answer the question: "when did the united states start doing daylight savings time?" whose answer is 1918.
Each document should contain about 30 words, and these documents should contain useful information.

Query: when did the united states start consistently observing daylight saving time
Useful Output:

Doc 1: Why do we change the clocks? The U.S. has been observing daylight saving time since 1918, with the passage of the Standard Time Act
Doc 2: In the United States, daylight saving time was first used in 1918  In 2007, the start and end of daylight saving time shifted again.
Doc 3: The United States established standard time zones and DST through the Calder Act, also known as the Standard Time Act of 1918. The issue of
Doc 4: It was unpopular and abolished after World War I. On Feb. 9 ,1942, Franklin Roosevelt instituted a year-round daylight saving time, which he
Doc 5: Daylight saving time was enacted by the Uniform Time Act of 1966, which also allows states to remain in standard time year-round.