The phase-out of ordinary incandescent bulbs -- those Edison-style bulbs with tungsten filaments -- began with the Energy Independence and Security Act signed by President George W. Bush in 2007. The measure didn't ban all incandescent bulbs, but required that they move toward 25% reductions in energy use over time. Specialty products such as three-way, chandelier and refrigerator bulbs were exempted.
Traditional bulbs had obvious inefficiencies, since 90% of the energy they used was dissipated as heat rather than light. They also burned out after months or even weeks of heavy use, producing waste.
The most common alternative, compact fluorescent bulbs or CFLs, were more expensive at the store, but more efficient, cooler and longer-lasting, so they saved consumers money in the long term. (These are the bulbs that look like small fluorescent tubes crammed into a spiral shape.)
CFL sales soared, but they also had their downsides -- they emitted a harsher light and also contained mercury, which made their disposal challenging.
The risk was modest in normal use, but environmental experts nevertheless recommended alarming precautions if one broke in the house: "Remove children and pets from the room, and then clean up the broken bulb as quickly as possible," advised the Environmental Defense Fund. "Increase the ventilation in the room where the bulb broke by opening windows and doors. ... To be extra safe, stay out of the area for a few hours to let any remaining mercury disperse."
So Trump wasn't exactly wrong when he talked about "hazardous waste." But he was behind the times. CFLs began to give way to less environmentally damaging LED bulbs in 2014 and were trailing them in sales by the beginning of 2016. CFLs are now almost entirely on the way out.
LEDs, meanwhile, have improved to the point that you can buy them in virtually any decorative style and intensities ranging from the hard white light of a security spot to the soft glow from under a living room lampshade. As for efficiency, they convert as much as 90% of their electricity into light.
Along the way, however, lightbulb regulations have become a right-wing cause, in part because the Obama administration had expanded and tightened the rules on incandescent bulbs.
In the Republican response to Barack Obama's 2011 State of the Union address, Rep. Michele Bachmann, R-Minn., railed against "a bureaucracy that now tells us which lightbulbs to buy."
Then-Rep. Joe Barton, R-Texas, a member of the Tea Party caucus, introduced a bill in 2011 to roll back the regulations. "This is about more than just energy consumption, it is about personal freedom," he said. "People don't want Congress dictating what light fixtures they can use."