Portage is a city in Kalamazoo County in the U.S. state of Michigan. The population was 46,292 in the 2010 census. It is the smaller of the two main cities included in the Kalamazoo-Portage Metropolitan Statistical Area, which has a population of 326,589 as of 2010.

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, along with three middle schools and eight elementary schools. In 2015, voters approved 144 million in bonds to go towards the school system. This money paid for two new middle schools and two new football stadiums, along with many other things like buses and swimming pools. The pharmaceutical company Pfizer also has manufacturing operations located there, which in recent years has caused much controversy due to layoffs. Stryker Corporation also has a large manufacturing presence in the city and is a worldwide leader in medical equipment, instruments and imaging technologies. Portage is also home to FEMA Corporation, a growing hydraulic valve manufacturing company.

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.

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According to the United States Census Bureau, the city has a total area of 35.17 square miles (91.09 km2), of which 32.23 square miles (83.48 km2) is land and 2.94 square miles (7.61 km2) is water.

Austin Lake is in the southeast part of the city and was named for Moses Austin, who had emigrated to Portage Township from Genesee County, New York in 1833. A settlement grew on the north shore of the lake, known as Austin or Austin Lake. A post office named "Austin's Lake" was established on May 18, 1850, with Austin as postmaster, and operated until August 15, 1853. The place was also a station on the Grand Rapids and Indiana Railroad in 1867.

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As of the census of 2010, there were 46,292 people, 19,199 households, and 12,426 families residing in the city. The population density was 1,436.3 inhabitants per square mile (554.6/km2). There were 20,559 housing units at an average density of 637.9 per square mile (246.3/km2). The racial makeup of the city was 86.9% White, 4.9% African American, 0.4% Native American, 3.8% Asian, 1.0% from other races, and 3.0% from two or more races. Hispanic or Latino of any race were 3.1% of the population.

There were 19,199 households of which 32.4% had children under the age of 18 living with them, 50.1% were married couples living together, 10.9% had a female householder with no husband present, 3.8% had a male householder with no wife present, and 35.3% were non-families. 29.1% of all households were made up of individuals and 10.5% had someone living alone who was 65 years of age or older. The average household size was 2.40 and the average family size was 2.98.

The median age in the city was 38.1 years. 24.8% of residents were under the age of 18; 7.9% were between the ages of 18 and 24; 26.7% were from 25 to 44; 26.9% were from 45 to 64; and 13.6% were 65 years of age or older. The gender makeup of the city was 47.9% male and 52.1% female.