At stores across the country, traditional light bulbs are slowly fading out.
Starting Wednesday, the U.S. will stop producing standard 40- and 60-watt incandescent bulbs, as the country works to shrink its carbon footprint.
The cutback is part of a 2007 energy efficiency law signed by former President George W. Bush which requires new bulbs to meet tighter standards.
Seventy-five- and 100-watt bulbs are already being phased out, which is an step forward according to Kit Kennedy of the National Resources Defense Council.
"The old fashioned incandescent bulb actually wastes 90 percent of the energy it uses,” Kennedy said. “Instead of going to light, it goes to waste heat and that means there's a lot more power plant pollution, and it also means that we pay more on our utility bills."
According to the federal government, energy efficient bulbs, like LEDs, halogens and compact fluorescents use about 25 to 80 percent less energy, and last up to 25 times longer.
While the new bulbs cost more at the register, the department of energy estimates American homeowners will save billions in the long run.
"I think it's the cheapest thing you can implement as a homeowner that would drop your energy bill,” said Dan Hersch of the Department of Energy. “If they're using one-fourth the energy to produce the same amount of light, that's significant savings."
Still, not everyone is ready to make the switch.
According to a recent survey, 30 percent of consumers plan to load up on incandescent bulbs while they are still available.
As the countdown began, Americans were tweeting pictures of their stockpile.
For now, stores will be allowed to continue selling traditional bulbs, at least while supplies last.