From street lights to city parks, community centers and fire stations, all Las Vegas city-run spots are now powered entirely by renewable energy, making it the largest in the U.S. to use such sources.

"We are now one of the few cities of the world that can say all the power we use comes from a green source," Mayor Carolyn G. Goodman said during a press conference on Monday.

The goal was reached with last week's opening of Boulder Solar 1, a large solar plant run by NV Energy that's located near Las Vegas.

"This is truly a proud day for Las Vegas,” Mayor Carolyn G. Goodman said.

Renewable energy is generated from natural processes that are continuously replenished, according to Penn State University. "This includes sunlight, geothermal heat, wind, tides, water, and various forms of biomass. This energy cannot be exhausted and is constantly renewed," the school said.

While all Vegas government facilities are now only powered by renewable energy, many residential and commercial buildings are not, the Huffington Post reported.

In total, this transition to renewable energy is estimated to save the city around $5 million per year in energy spending. The city invested more than $40 million in renewable energy over the past few years.

San Francisco and San Jose are some of the other big cities with plans to use 100% renewable energy by 2035, the Sierra Club reported.