The City of Seaside is at the mouth of the Necanicum River on Oregon's north coast. The Necanicum River orginates at Saddle Mountain in southern Clatsop County and runs north and south through Seaside. The area encompasses approximately 3.9 square miles of land and 0.2 square miles of surface water. Seaside is located 80 miles northwest of Portland and 17 miles south of Astoria.

According to the Certified 2009 Population Estimate the population of Seaside was 6480, and the 2000 Census figures were listed with a poluation of 5900.

Seaside is an incorporated city that operates under a Council-Mayor government. A Mayor and six City Council members represent the community.

The main roads connecting Seaside to neighboring communities include state highway 101 south to Cannon Beach and state highway 26 southeast to Portland and North of Astoria. The Portland International Airport, 80 miles southeast of Seaside, is the closest airport offering commercial and international service. The Seaside municipal airport is accessible by light single engine and twin aircraft only. The nearest ports are 17 miles northwest in Astoria and 15 miles north in Hammond.

The Seaside School District offers K-12 education to over 1500 students in the area. Clatsop Community College, a public, two-year institution is located approximately 17 miles north in Astoria and serves over 10,000 students. Pacific Power and Light and Northwest Natural Gas are the primary electricity and gas providers for the City. The City of Seaside provides the community and residents with water and sewer services. Public safety in Seaside is administered by the Seaside Police Department and the Seaside Fire Department. Seaside is home to Providence Seaside Hospital which offers physician coverage and emergency services.

There are several community businesses including the Seaside Aquarium, founded in 1937, and is one of the oldest aquariums on the West Coast, the City of Seaside Library (newly built in 2008), the Seaside Historical Society Museum, Sunset Empire Parks and Recreation (with a pool and indoor youth center), and several recreation activities and places of worship.