The Act of 1871 as you are calling it is not its full name. It’s action name is the District of Columbia Organic Act of 1871. It established a new, unified government for Washington, D.C. It “incorporated” that city, a common legal term by which areas are organized for governance by a single entity. In this case, two cities and a county were merged into the District of Columbia. It made no changes in the nation as a whole.
A PDF pith text of the legislation
Typo
Action = actual
Yes, thank you, but let’s face it, the precise name is irrelevant to having an understanding of its effects and it gets old reading the “action name,” as you call it, again and again.
The act made drastic changes to our nation in that it allowed three sovereign states to work together to enslave us.
The City of London, Vatican City and Washington, D.C.