Megaregions of the United States in the context of "Texas Triangle"

Northern California (commonly shortened to NorCal) is a geocultural region that comprises the northern portion of the U.S. state of California, spanning the northernmost 48 of the state's 58 counties. Northern California in its largest definition is determined by dividing the state into two regions, the other being Southern California. The main northern population centers include the San Francisco Bay Area (anchored by the cities of San Jose, San Francisco, and Oakland), the Greater Sacramento area (anchored by the state capital Sacramento), the Redding, California, area south of the Cascade Range, and the Metropolitan Fresno area (anchored by the city of Fresno). Northern California is coterminous with the natural range of the coast redwood and the giant sequoia, with many well-known old-growth forests and smaller groves. It contains most of the Sierra Nevada, including Yosemite Valley and part of Lake Tahoe, Mount Shasta (the second-highest peak in the Cascade Range after Mount Rainier in Washington), and most of the Central Valley, one of the world's most productive agricultural regions. Northern California is also home to Silicon Valley, the global headquarters for several of the largest most powerful companies in the world, including Alphabet Inc. (Google), Apple, Meta, and Nvidia.

The Northern California Megaregion, one of the 11 megaregions of the United States is centered in Northern California, and extends from Metropolitan Fresno north to Greater Sacramento, and from the Bay Area east across the Nevada state line to encompass the entire Lake Tahoe–Reno area.

The Southern Rocky Mountain Front is a megaregion of the United States, otherwise known as a megalopolis, with population centers consisting mainly of the Front Range Urban Corridor and the Albuquerque–Santa Fe–Los Alamos combined statistical area, located along the eastern and southern face of the Southern Rocky Mountains in the U.S. states of Wyoming, Colorado, and New Mexico. The region comprises the southern portion of the Rocky Mountain Front geographic region of Canada and the United States, extending into the Southwestern United States. The Southern Rocky Mountain Front had a population of 5,467,633 according to the 2010 United States census. The region is one of the fastest-growing regions in the United States, and its population is projected to grow by 87% to 10,222,370 by 2050. In 2005 the GDP of the region was $229,202,000,000 making up 2% of the United States GDP.

The Arizona Sun Corridor, shortened Sun Corridor, is a megaregion, or megapolitan area, in the southern area of the U.S. state of Arizona - comprising approximately 85 percent of the state's population. The Sun Corridor is comparable to Indiana in both size and population. It is one of the fastest growing conurbations in the country. The largest metropolitan areas are the Phoenix metropolitan area – Valley of the Sun, and the Tucson metropolitan area – The Old Pueblo. The regions' populace is nestled in the valley of a desert environment. Similar to Southern California, the urban area extends into Mexico, reaching the communities of Heroica Nogales and Agua Prieta.

Its population is composed of five metropolitan areas: Phoenix, Tucson, Prescott, Sierra Vista-Douglas and Nogales. Of these, two are metropolitan areas with over 1,000,000 residents: the Phoenix metropolitan area with 4.85 million residents and the Tucson metropolitan area with over 1 million residents. The Arizona Sun Corridor is made up of all of Maricopa, Pinal and Pima counties, along with parts of Yavapai, Santa Cruz and Cochise counties. It is home to over 86 percent of Arizona's population.