The group of related cultures called the Mound Builders has begun to flourish in the Mississippi river valley.

Mound Builders is a general term referring to the native peoples who construct various styles of earthen mounds for burial and for residential and ceremonial purposes, typically flat-topped pyramids or platform mounds, flat-topped or rounded cones, elongated ridges, and sometimes a variety of other forms.

Several hundred of the so-called Mississippian societies appear by 900 in the Mississippi Valley and its major tributaries, stretching from Saint Louis, Missouri to …

As settlers pour in to the frontier districts, they first become territories, with an elected legislature and a governor appointed by the president.

Then, when population reaches one hundred, thousand the territories apply for statehood.

Frontiersmen typically drop the legalistic formalities and restrictive franchise favored by eastern upper classes, and adopt more democracy and more egalitarianism.

In 1800 the western frontier reaches the Mississippi River.

St. Louis, Missouri, is the largest town on the frontier, the gateway for travel westward, and a principal trading center for Mississippi River traffic and inland commerce but remains under Spanish control until 1803.

A formal ceremony is conducted in St. Louis on March 10, 1804, to transfer ownership of the Louisiana Territory from France to the United States.

The Treaty of St. Louis is signed on November 3, 1804, by Quashquame, a Sauk chief, and William Henry Harrison, the governor of Indiana Territory.

Quashquame maintains two large villages of Sauk and Meskwaki near the modern towns of Nauvoo, Illinois and Montrose, Iowa, and a village or camp in Cooper County, Missouri.

Black Hawk, a frequent visitor to Quashquame's village, will lament this treaty in his autobiography.

The Sauk and Meskwaki delegation had been sent to surrender a murder suspect and make amends for the killing, not to conduct land treaties.

Controversy surrounding the treaty will eventually cause the Sauk people to ally with the British during the War of 1812, and is the main cause of the Black Hawk War of 1832.

The Lewis and Clark Expedition reaches St. Louis, Missouri, ending a successful exploration of the Louisiana Territory and the Pacific Northwest.

According to one historian, their arrival comes "much to the amazement of residents, who had given the travelers up for dead." (Lee Ann Sandweiss, Seeking St. Louis: Voices from a River City, 1670-2000 (Missouri History Museum, 2000) p41)

The Missouri Territory, originally known as the Louisiana Territory, is renamed by the U.S. Congress in June 4, 1812, to avoid confusion with the new state of Louisiana, which had joined the Union on April 30 of this year.

Governor William Clark organizes the five administrative districts of the former Louisiana Territory on October 1, 1812, into counties, which will later become the first five counties of the state of Missouri.

The Saint Louis Academy, which will later become Saint Louis University, is founded on November 16, 1818 by the Most Reverend Louis William Valentine Dubourg, Bishop of Louisiana and the Floridas, using his personal library of eight thousand volumes for its printed materials.

Today a private Roman Catholic four-year research university with campuses in St. Louis, Missouri, United States and Madrid, Spain.

It is the oldest university west of the Mississippi River and the second-oldest Jesuit university in the United States.

...the Missouri constitutional convention empowers the state legislature to exclude free blacks and mulattoes.

Enough northern congressmen object to the racial provision that Henry Clay is called upon to formulate the Second Missouri Compromise.