Eastern California is a region defined as either the strip to the east of the crest of the Sierra Nevada or as the easternmost counties of California. Demographics According to the 2010 census, the population of the eastern border counties of California was 5,129,384. However, 4,224,851 (82.4%) lived in San Bernardino and Riverside counties, which are very large and whose populations are concentrated near Los Angeles and Orange counties to the southwest. Culture and history Eastern California's history differs significantly from that of the coastal regions and the Central Valley. Northeastern California is very sparsely populated (except for the area around Lake Tahoe): the three least-populated counties of California lie in the northeast. The area tends to be politically conservative, much like the rest of the rural Western United States. However, the counties of San Bernardino and Riverside form the 13th-largest metropolitan area of the United States, and El Dorado and Placer Counties are part of the Greater Sacramento area and are culturally influenced by their respective metropolitan areas. Imperial County in the Southeast, though rural and agrarian, is heavily Democratic and has ties with the Mexicali Valley to the south. Northeastern California has had strong ties to Nevada, with the exact boundary between the two states having once been a matter of dispute. Residents of an area near Susanville, California tried to break away from the state in 1856, first by declaring themselves part of the Nataqua Territory and then through annexation to Nevada. The two states further squabbled over ownership of Susanville in 1863. The town of Aurora, Nevada, was temporarily the county seat of both Mono County, California, and Esmeralda County, Nevada. Finally, the line between the two states was settled by a survey in 1892. Over time, droughts and wildfires have increased in frequency and become less seasonal and more year-round, further straining the region's water security. There are many unique historical aspects of Eastern California including the Manzanar internment camp and the historical Carson and Colorado Railway. Geography The easternmost counties of California are (from north to south): Modoc County Lassen County Plumas County Sierra County Nevada County Placer County El Dorado County Alpine County Mono County Inyo County San Bernardino County Riverside County Imperial County Cities within this region include San Bernardino, Riverside, Ontario, Corona, Rancho Cucamonga, Roseville, Victorville, Temecula, Palm Springs, Lincoln, El Centro, Barstow, South Lake Tahoe, Susanville, Truckee, Grass Valley, Placerville,