The district courts were established by Congress under Article III of the United States Constitution.The courts hear civil and criminal cases, and each is paired with a bankruptcy court. Appeals from the district courts are made to one of the 13 courts of appeals, organized geographically.The number of district courts in a court of appeals’ circuit varies between one and thirteen, depending on …
https://en.wikipedia.org/wiki/List_of_United_States_district_and_territorial_courts

