What flatlands circle the gulfline of the northern and western coastline of Mexico?

The flatlands that circle the Gulf line of the northern and western coastline of Mexico are primarily the Gulf Coastal Plain. This region features low-lying terrain and extends from the southern tip of Texas along the eastern coast of Mexico down to the Yucatán Peninsula. The area is characterized by its wetlands, estuaries, and a mix of coastal ecosystems. Additionally, the coastal plain supports significant agricultural activities and is home to various urban centers.