Amarillo is the largest city and commercial center of the Texas Panhandle. It is located about 360 miles west of Dallas. It was incorporated in 1892 and is the seat of Potter County. Part of the city extends into Randall County. Amarillo was laid out by developer Henry B. Sanborn after the arrival of the Fort Worth and Denver City Railroad in 1887. It quickly became a cattle shipping center. After the turn of the 20th century, the cotton industry became important. Industrial growth followed the discovery of oil in the Panhandle in 1921. Today, Amarillo is a processing and distribution center for cattle and oil products. It lies in the world's largest helium producing area. Manufacturing, education, government, and healthcare are also important to the economy.