I have to routinely show this map because there are so many new followers. This is an 1894 map by the Smithsonian's Bureau of Ethnology showing the mound sites they had identified at that time--but only in the eastern half of the USA. The red dots are sites, many with multiple
LiDAR of the "Circle & Octagon" earthworks in Newark, Ohio. The circle encloses 20 acres and the octagon 50 acres. The outer walls are 8-16 feet high. Note the 8 small truncated rectangular mounds at each point the octagon walls create small gaps. It was probably made ~ A.D. 200.
One of the finest aerial photos I've ever seen of a Native American mound showing how massive the mound really is. That is me walking down the ramp. When in use a thousand years ago, there was a large temple structure on the top. This is the largest mound at the [once] 23-mound
Illustration of a 10.5 inch square embossed copper sheet excavated from the Mount Royal mound site in Florida by C. B. Moore in 1873. It had a reed mat on the back and a second copper sheet was attached to its other side.