Portland is a city in and the county seat of Jay County, Indiana, United States. The population was 6,223 at the 2010 census, and in 2018 the estimated population was 6,085.
Portland was platted in 1837. It was named after Portland, Maine.
The Jay County Courthouse, Portland Commercial Historic District, and Jonas Votaw House are listed on the National Register of Historic Places.
Portland is located in central Jay County at 40°26′2″N 84°58′48″W (40.433884, -84.979914), along the Salamonie River. U.S. Route 27 (Meridian Street) runs through the center of the city, leading north 49 miles (79 km) to Fort Wayne and south 43 miles (69 km) to Richmond. Indiana State Road 26 enters Portland from the west on Votaw Street and from the east on Water Street; SR-26 leads west 21 miles (34 km) to Hartford City and east 10 miles (16 km) to the Ohio border near Fort Recovery. Indiana State Road 67 follows SR-26 west out of Portland, then leads southwest 29 miles (47 km) to Muncie.
According to the U.S. Census Bureau, Portland has a total area of 4.97 square miles (12.88 km2), of which 1.6 acres (6,524 m2), or 0.05%, are water. The Salamonie River runs through the city just south of its center. The Salamonie is a west-flowing tributary of the Wabash River.
At the 2010 census there were 6,223 people, 2,607 households, and 1,620 families living in the city.