100,000 square milesClick to see full answer. Likewise, what does the Gulf Coastal Plain contain?The West Gulf Coastal Plain has several distinctive features, including extensive areas of loblolly-shortleaf pine forests; level to rolling terrain; deposits of sand and gravel; and industrially significant deposits of clay, bauxite, and petroleum.Secondly, what is the Coastal Plains population? 4.5 million people Simply so, what is the climate in the Gulf coastal plain? The Gulf Coastal Plains borders the Gulf of Mexico, which gives it its low marshy coasts. It has hot humid summers and mild winters. It recieves lots of rain, about fifty inches per year and because of its hot weather, it recieves little snow.What are the major cities in the Gulf Coastal Plains?There are also major cities in the Gulf Coast Plains. The major cities are Corpus Christi, Galveston, Houston, San Antonio, Baytown, Alvin, Port Arthur, Beaumont, Port Isabel, Victoria, Wharton, Raymondville, and Sugarland.