The Northwest League of Professional Baseball (or simply the Northwest League or NWL) is a Class A-Short Season minor baseball league. The league is the descendant of the Western International League which ran as a class B league from 1937-1951 (with time out for World War II) and class A from 1952-1954. The league changed its name and dropped back down to class B for the 1955 season. The Northwest League (or the Northwestern League) has existed in various forms since 1901, and has been in its current incarnation since 1955.