Serpent Mound, Adams County, Ohio. 

Postcard - Published by the Ohio State Museum, Columbus. No date.

One of the few effigy mounds in Ohio, Serpent Mound is the largest and finest serpent effigy in the United States. Nearly a quarter of a mile long, Serpent Mound apparently represents an uncoiling serpent. Serpent Mound lies on a plateau overlooking the valley of Brush Creek. Nearby conical mounds contained burials and implements characteristic of the prehistoric Adena people (800 BC-AD 100).  

Atop a plateau overlooking the Brush Creek Valley, Serpent Mound is the largest and finest serpent effigy in the United States. Nearly a quarter of a mile long, Serpent Mound apparently represents an uncoiling serpent.

In the late nineteenth-century Harvard University archaeologist Frederic Ward Putnam excavated Serpent Mound and attributed the creation of the effigy to the builders of the two nearby burial mounds, which he also excavated. We now refer to this culture as the Adena (800 BC-AD 100). A third burial mound at the park and a village site near the effigy's tail belong to the Fort Ancient culture (AD 1000-1550).

The head of the serpent is aligned to the summer solstice sunset and the coils also may point to the winter solstice sunrise and the equinox sunrise. Today, visitors may walk along a footpath surrounding the serpent and experience the mystery and power of this monumental effigy. A public park for more than a century, Serpent Mound attracts visitors from all over the world. The museum contains exhibits on the effigy mound and the geology of the surrounding area.

Card #2 - Art Mfg. Co., Amelia, Ohio. No date.

Many questions surround the meaning of Serpent Mound, but there is little doubt it symbolized some religious or mythical principle for its builders.

source: http://www.ohiohistory.org/places/serpent/

Cahokia Mounds State Historic Park, Illinois

A thousand years ago, a civilization more sophisticated and more powerful than any other in the Western Hemisphere north of Mexico grew up and florished in the rich Mississippi River bottom land of southwestern Illinois. These native American people - called Mississippians by archaeologists - supported a population as large as 20,000 at their zenith with a wid-scale agricultal economy based primarily on the cultivation of corn. The crops they grew combined with the region's bountiful wildlife and indigenous plants to form a stable, year-round food supply. Such stability and ties to the land gave rise to the formation of permanent settlements that grew into an extensive network of communities with a regional center of metropolitan proportions.

The sedentary lifestyle of the Mississippians made possible other hallmarks of advanced civilization: widespread commerce; stratifed social, political, and religious organization; specialized and refined crafts; and monumental architecture, here in the form of earthen mounds covering up to 14 acres and rising as high as 100 feet.

Their extraordinary success continued for five centuries until, for reasons still unknown, the sun set on the Mississippians as it had on the great Mayan, Egyptian and Mesopotamian people before them. Finally, when agencies of the state of Illinois carried out the first scientific investigations of the area in the 1920s, the true extent of this vibrant culture began to emerge.

The remnants of the Mississippian's central city - now known as Cahokia for the Indians who lived nearby in the late 1600s - are preserved within the 2200-acre tract that is the Cahokia Mounds State Historic Site. Located just eight miles east of downtown St. Louis, Missouri, near Collinsville, Illinois, Cahokia was designated a World Heritage Site in 1982 by the United Nations Educational, Scientific, and Cultural Organization (UNESCO) for its vital contribution the understanding of North American prehistory.

source: http://medinfo.wustl.edu/~mckinney/cahokia/Introduction.html