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There are plenty of major U.S. cities that somehow thrive in the desert. Thanks to modern infrastructure, cities with over one million residents make their way in what once was considered uninhabitable. Here are the five driest cities in the U.S.

Los Angeles, California

Los Angeles, California, USA downtown cityscape at sunny day
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Who would have thought that the second-largest city in the country would also be one of the driest? Coming in as the fifth-driest large city in the nation, Los Angeles only gets an average of 12.8 inches of precipitation a year. So with that little water, how does this city of roughly four million people get by? Thankfully, there is some serious infrastructure in place to get water to these millions of residents. From drinking water to maintaining landscaping, all the water to sustain this massive city comes from elsewhere.

The first main source of water is water from the Owens River. This water collects in Mono Lake near Yosemite and other reservoirs in the Sierra Nevada Mountains. The water makes its way to Los Angeles via the Los Angeles Aqueduct — about 430 million gallons daily, to be exact. This incredible amount of water accounts for about one-third of the Los Angeles water supply. The Sierra Nevada snowpack would be another source of water. Still, it's not nearly enough to support Los Angeles, let alone Southern California. So, the Colorado River Aqueduct brings about half of Los Angeles's water to the city from the Colorado River.

San Diego, California

San Diego skyline with water in foreground
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Much like the predicament we see in Los Angeles, San Diego is a city that popped up in the desert. Sure, it's on the beach, and the days are sunny and warm. But it's also dry, dry, dry — it gets barely over 10 inches of rain per year. That's not enough water for its nearly 1.5 million residents. This dry city is also a hot destination for tourists. So, where does the water come from for this city?

San Diego has to purchase 80% to 90% of its water from Northern California and the Colorado River. Water gets to San Diego from these sources via aqueducts. Because this means water prices can get up there for the locals, San Diego is doing its best to figure out how they can use more of their groundwater. According to the city, they are in the process of creating basins to collect groundwater and have it processed for public use. They also get water from the Claude "Bud" Lewis Carlsbad Desalination Plant, which turns salt water from the ocean into usable freshwater.

Riverside, California

City of Riverside, California with palm trees and mountains in the background
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Riverside is another California city that doesn't see very much rain. It has the same average rainfall as San Diego, about 10.3 inches per year. Unlike San Diego, however, Riverside has a much smaller population to support, and it has an excellent system for collecting groundwater for the community to use.

Bunker Hill and Riverside Basin are two regional collection areas for rainwater and snowmelt that provide water for the entire city. How do they work? Water settles into pools deep in the earth. Then, Riverside relies on 54 wells operated by Riverside Public Utilities to provide the city with all of their water needs. Although the rain is sparse, these basins collect it effectively.

Phoenix, Arizona

Phoenix, Arizona, with its downtown lit by the last rays of sun at the dusk
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Everyone knows Phoenix is in the middle of the desert. So it should come as no surprise that it's the second driest city in the United States. If you go to Phoenix, you'll see a massive city of over 1.6 million people and lots of sand, rocks, and cacti. Do you know what you won't see? Rain. Phoenix only gets 8.04 inches of rainfall each year. As the city grew, officials knew they would need major infrastructure to support the water needs of this metropolis.

Today, Phoenix gets most of its water from two sources. The first is the Salt River Project, which imports water via pipeline from the Verde and Salt Rivers. The second is the Central Arizona Project, which brings water from the Colorado River to Phoenix and the surrounding area. Since Phoenix doesn't fool anyone about its climate and has always been a desert, the city has long diversified its water portfolio to prevent drought. Phoenix's government website asserts:

"Phoenix's water supply is good, but it is important to conserve water as a lifestyle. It's everyone's job to think about water … every time you use it … and use it responsibly. Phoenix has the water it needs — but none to waste."

Las Vegas, Nevada

Aerial view of Las Vegas, Nevada at night
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The number one spot on this list should come as no surprise. Las Vegas is the driest city in the U.S. What might surprise you, though, is how little rainwater it truly gets — only an average of 4.2 inches per year. Las Vegas is a city with over 640,000 residents and a staggering 42 million tourists each year. The opulence of this town just doesn't seem plausible for a desert considering the lack of such a vital resource. So how do they do it?

Las Vegas and South Nevada get 90% of their water from the Colorado River. Nearly all of these cities we've mentioned are reliant on the Colorado River, which begins in Colorado in the Rocky Mountains, and flows for 1,450 miles until it reaches the Gulf of California in Mexico. The other 10% of Las Vegas water comes from groundwater. And when the demands for water are highest during the summer, groundwater provides up to 25% of the water needed.