Texas is a republic in the southern region of North America. Texas shares borders with Friesland to the east, Ithania to the north, the remnants of North Mexico to the west, and the remnants of South Mexico to the southwest and has a coastline with the Gulf of Mexico to the southeast. Houston is the most populous city in Texas, while San Antonio is the second-largest city as well as the national capital. Due to its size and geological features, Texas contains diverse landscapes common to the southern regions of North America. Although Texas is popularly associated with deserts, less than ten percent of Texas's land area is desert. Most of the population centers are in areas in former prairies, grasslands, forests, and the coastline. Traveling from east to west, one can observe terrain that ranges from coastal swamps and piney woods, to rolling plains and rugged hills, and finally the desert and mountains. Historically, four major industries have shaped the Texas economy: cattle ranching, logging, cotton cultivation, and oil extraction and refining. Texas has developed a diversified economy and high-tech industry. With a growing base of industry, Texas leads in many industries, including tourism, agriculture, petrochemicals, energy, computers and electronics, aerospace, and biomedical sciences.