U.S. President George Bush signed into law on Monday an energy bill that would extend daylight saving time by one month -- a change that could impact how business is done between Canada and the United States in the spring and fall.

Previously, most of Canada and the United States have followed the same daylight time -- from the first Sunday in April to the last Sunday in October.

Starting in 2007, daylight time in the United States will now start on the second Sunday in March, and go to the first Sunday in November.

The provision to change daylight saving time is a clause in the Energy Policy Act of 2005. The congressmen who sponsored the change -- Michigan's Fred Upton and Massachusetts's Ed Markey -- say it could help curb energy use.

Bush said the bill "launches an energy strategy for the 21st century."

"This bill will strengthen our economy, and it will improve our environment, and it's going to make our country more secure," Bush said, in announcing the signing of the bill.

It's unclear if Canada will make the same time change. At least one business leader believes Ottawa has no choice but to follow the United States.

"Obviously, the Canadian economy and the U.S. economy are so integrated now that for us to be out of sync with one another I think will cause some severe problems," Len Crispino, president and CEO of the Ontario Chamber of Commerce, recently told CTV Newsnet.

The change could have implications for the airline industry, the Toronto Stock Exchange, and the automotive sector, since many automotive manufacturers use "just-in-time" delivery systems to get car parts to plants.

It could also have an impact on machines such as VCR's, DVD's and computers that automatically compensate for daylight time based on the previous schedule.

Upgrades for Microsoft Corp.'s Windows operating systems would likely be available, but if Canada didn't follow the time change, the software would have to learn additional zones.

The energy bill originally called for a two-month extension of daylight time. It was pared down after farmers complained of the impact on livestock, and airlines said it would have complicated international flight schedules.