Invention and Engineering
California is a state in the Western United States. It is bordered by Oregon to the north, the Mexican state of Baja California to the south, Nevada to the east, Arizona to the southeast, and the Pacific Ocean to the west. With a population of over 39 million across an area of 163,696 square miles (423,970 km2), it is the most populous U.S. state and the third largest by land area. Before European colonization, California was one of the most culturally and linguistically diverse areas in pre-Columbian North America. European exploration in the 16th and 17th centuries led to the colonization by the Spanish Empire. The area became a part of Mexico in 1821, as a result of its successful war for independence. Following the U.S. conquest of California, part of the Mexican-American War, California was ceded to the United States in 1848. The California gold rush started in 1848 and led to social and demographic changes, including the California genocide. It organized itself and was admitted as the 31st state in 1850 as a free state, following the Compromise of 1850. Greater Los Angeles and the San Francisco Bay Area are the nation's second and fifth most populous combined statistical areas. Los Angeles is the state's most populous city and is ranked second in population in the nation. California's capital is Sacramento. Part of the Californias region of North America, the state's diverse geography ranges from the Pacific Coast and metropolitan areas in the west to the Sierra Nevada mountains in the east, and from the redwood and Douglas fir forests in the northwest to the Mojave Desert in the southeast. Two-thirds of the nation's earthquake risk lies in California. The Central Valley, a fertile agricultural area, dominates the state's center. The large size of the state results in climates that vary from moist temperate rainforest in the north to arid desert in the interior, as well as snowy alpine in the mountains. While California is warming and drying overall, with frequent wildfires, the state is also experiencing increasing weather whiplash. The economy of California is the largest of any U.S. state, with an estimated 2025 gross state product of $4.296 trillion as of Q3 2025.
GCR Class 9Q.
Indian locomotive class WAP-5.
Text from Wikipedia; plate via Wikimedia Commons. Text CC BY-SA 4.0; plate freely licensed (see Commons). Source record. Images and catalogue data are reproduced from open-access collections.