The large size of the current court is because 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 …
https://en.wikipedia.org/wiki/United_States_Court_of_Appeals_for_the_Ninth_Circuit

