The large size of the current court is due to the fact that both the population of the western states and the geographic jurisdiction of the Ninth Circuit have increased dramatically since the U.S. Congress created the United States Court of Appeals for the Ninth Circuit in 1891. The court was originally granted appellate jurisdiction over federal district courts in California, Idaho, Montana, Nevada, Oregon, and Washington. As new states and territories were added to the federal judicial hierarchy in the twentieth century, many of those in the West were placed in the Ninth Circuit: the newly acquired Territory of Hawaii in 1900, Arizona upon its admission to the Union in 1912, the Territory of Alaska in 1948, Guam in 1951, and the Commonwealth of the Northern Mariana Islands in 1977.