In 1824, three years after Florida became a US territory, swampy Mosquito County was established. The first US settlers arrived in 1837, and in 1838 the US military built Fort Gatlin as a base for the Seminole Indian Wars. Upon Florida statehood in 1845, Mosquito County changed names to the far more alluring Orange County. Orlando grew and in 1875 the 2-sq-mile city (population 85) was officially incorporated. With the arrival of the railroad in 1880, the region became a popular orange-growing and tourist center. WWII brought air bases and missile building, but it was the 1971 opening of Walt Disney World® Magic Kingdom that paved the way to the city's contemporary reputation as the theme-park capital of the US. Today, it is the USA's number-one travel destination.