Which act set up regional courts for US?

Congress established the US Courts of Appeals under the Evarts Act (Judiciary Act) of 1801, assigning one court for each of the nine judicial circuits. The Evarts Act reduced the Supreme Court's caseload at a time when the justices lacked judicial discretion (the ability to choose which cases they hear), an important development in the history of the federal judiciary.

The Courts of Appeals officially adopted the name US Court of Appeals Circuit Courts in the judicial code of 1948.

There are currently thirteen US Courts of Appeals Circuits, numbered First through Eleventh (e.g., US Court of Appeals for the Eleventh Circuit), plus the District of Columbia Circuit and the Federal Circuit.