Amarillo (/ˌæməˈrɪloʊ/ AM-ə-RIL-oh) is the 14th-most populous city in the state of Texas, United States. It is also the largest city in the Texas Panhandle, and the seat of Potter County. A portion of the city extends into Randall County. The estimated population was 199,826 as of 2017. The Amarillo metropolitan area has an estimated population of 276,020 in four counties as of 2017. The metro population is projected to surpass 310,000 in 2020. Amarillo, originally named Oneida, is situated in the Llano Estacado region. The availability of the railroad and freight service provided by the Fort Worth and Denver City Railroad contributed to the city's growth as a cattle-marketing center in the late 19th century. The city was once the self-proclaimed "Helium Capital of the World" for having one of the country's most productive helium fields. The city is also known as "The Yellow Rose of Texas" (as the city takes its name from the Spanish word for yellow), and most recently "Rotor City, USA" for its V-22 Osprey hybrid aircraft assembly plant, as well as "Bomb City". Amarillo operates one of the largest meat-packing areas in the United States. Pantex, the only nuclear weapons assembly and disassembly facility in the country, is also a major employer. The location of this facility also gave rise to the nickname Bomb City. The attractions Cadillac Ranch and Big Texan Steak Ranch are located adjacent to Interstate 40. U.S. Highway 66 also passed through the city.