Short answers, pulled from the story.
The Census Bureau defines the Western United States as 13 states split into two divisions. The Mountain states are Montana, Wyoming, Colorado, New Mexico, Idaho, Utah, Arizona, and Nevada. The Pacific states are Washington, Oregon, California, Alaska, and Hawaii.
The Western United States covers nearly half the land area of the contiguous United States, making it the largest of the four census regions. It is also the most geographically diverse, holding temperate rainforests, the highest mountain ranges, and the majority of the country's deserts.
The 13 Western states had a total 2020 population of 78,588,572. The region remains one of the most sparsely settled in the country at 49.5 people per square mile, and as of 2022 just under half of its residents lived in California.
Because development had not reached most of the West when conservation became a national issue, federal agencies came to own and manage vast tracts. Public lands account for 25 to 75 percent of the total land area in the Western states, managed chiefly by the National Park Service, the Bureau of Land Management, and the U.S. Forest Service.
Death Valley, California is the driest place ever recorded in the United States. Most of the West is semi-arid, and parts are true desert that receive less than 5 inches of rain per year.
Before around 1800, the crest of the Appalachian Mountains was seen as the western frontier. As settlement pushed westward the frontier moved with it, until the lands west of the Mississippi River were considered the West.
The Western United States has produced three presidents: Herbert Hoover, Richard Nixon, and Ronald Reagan. The region was also the first to see widespread women's suffrage, with women voting in Utah and Wyoming as early as 1870.