The U.S. House of Representatives voted overwhelmingly to pass a bill making daylight saving time permanent.

The Senate must still pass it before it can become law.

President Donald Trump has indicated support.

The bill would end the twice-yearly clock change in spring and fall.

An AP-NORC poll last year found only 12% of American adults favored the current system.

Almost half opposed it.

Proponents of a single time include the American Medical Association and the American Academy of Sleep Medicine.

America tried permanent daylight saving time before, in the 1970s.

Congress passed a law in 1973 for a trial from January 1974 to April 1975.

It lasted only until October 1974, when public outcry led to its repeal.

A major concern was that schoolchildren would have to go to school in darkness.

Kevin Birth, a professor at Queens College, remembers the experience vividly.

He said it was "pitch black" into the school day.

Birth said more than just clocks must change if the U.S. tries again.

The current four time zones would need adaptation, as sunrise times vary greatly within each zone.