Editing Cahokia, Illinois (section)

===Northwest Ordinance===
After Congress passed the [[Northwest Ordinance]] in 1787 and established a governmental system for the territory, the [[Cahokia Courthouse]] was adapted for use as a United States territorial courthouse. Cahokia continued as a major political center for the next 24 years. Flood-prone Kaskaskia became the governmental seat of the [[Illinois Territory]] (1809–1818), until the territorial seat was moved to [[Vandalia, Illinois]], and in 1809 became the county seat of [[Randolph County, Illinois|Randolph County]]. Cahokia became the seat of St. Clair County, named by and after [[Arthur St. Clair]], the first territorial governor. When St. Clair County was enlarged in 1801 and 1809, Governor [[William Henry Harrison]] (and later territorial secretary and acting governor [[Nathaniel Pope]]) named the Cahokia Courthouse as the legal and governmental center of a sizeable area extending to the Canada–U.S. border. By 1814, other counties and territories had been organized, and St. Clair County became its current size. The county seat was moved to the more centrally located [[Belleville, Illinois]], (incorporated 1819 and as a city in 1850) when a local developer offered to donate land for a new county courthouse and seat.