Found almost entirely within the United States, the North American Coastal Plain reaches from a small section of northern Mexico along the Gulf of Mexico and up the East Coast to southeastern Massachusetts. This region has long been misunderstood, which is why it was not classified as a biodiversity hotspot until 2016. Despite the 1,816 endemic plant species and the 1.13 million square kilometers of area, the hotspot has a low level of geographic variety and an unusually low level of elevation change when compared to the other hotspots, leading the scientific community to assume it would be less biodiverse.

The North American Coastal Plain is a fire-dependent region. When early European settlers first came to the area, they thought local Native American tribes started the periodic fires. In reality, the fires were not only natural but needed by the plant and animal species in the region, which had evolved to depend on them.