Everybody knows about the Northwest Ordinance, which was reaffirmed by the first Congress under the new Constitution. But did they do anything else that had a major effect after 1789?
The Confederation Congress set up the federal court system, which was then continued under the Constitution (with expanded jurisdiction).
Hmm, my understanding is that the Judiciary Act of 1789 bears little resemblance to the (quite limited) federal judiciary under the Confederation, but my knowledge here is extremely limited.
It would be more accurate to say that the Confederation Congress set up a federal court system. The Court of Appeals In Cases of Capture was the first federal court, but was actually created by the Continental Congress prior to ratification of the Articles of Confederation. The Confederation Congress established ad hoc courts that dealt only with interstate border disputes, but none of these survived the adoption of the Constitution. The federal judiciary as we know it today is “all new.”