In United States law, an organic act is an act of the United States Congress that establishes an administrative agency or local government, for example, the laws that established territory of the United States and specified how they are to be governed, or established agency to manage certain federal lands. In the absence of organic law, the body of laws that define and establish a government, a territory is classified as unorganized.
The first such act was the Northwest Ordinance, passed in 1787 by the U.S. Congress of the Confederation (under the Articles of Confederation, predecessor of the United States Constitution). The Northwest Ordinance created the Northwest Territory in the land west of Pennsylvania and northwest of the Ohio River and set the pattern of development that was followed for all subsequent territories. The Northwest Territory covered more than 260,000 square miles and included all of the modern states of Ohio, Indiana, Illinois, Michigan, Wisconsin, and the northeastern part of Minnesota.