Portage is a city in Kalamazoo County in the U.S. state of Michigan. The population was 44,897 at the 2000 census. Portage is adjacent to the southern boundary of the City of Kalamazoo. The city was incorporated from the entirety of the former Portage Township on December 31, 1963. There are two public high schools in Portage, Portage Central and Portage Northern. The pharmaceutical company Pfizer also has operations located there, which in recent years has caused much controversy due to layoffs. Portage is known for its extensive network of historical parks and trails used for cycling, walking, canoeing, and other recreational activities. Since the creation of the Portage Bikeway system in 1989, the trails have expanded to over 50 miles (80 km), over five times as long as the city’s expressways. Portage is also home to the Kalamazoo Air Zoo.