- Salem is the capital of the U.S. state of Oregon. It is located in the Willamette Valley region and has a population of approximately 175,000 people, making it the second-largest city in the state after Portland. Salem serves as the county seat of Marion County and is known for its government institutions, including the Oregon State Capitol. The city has a rich history and is home to numerous museums, parks, and cultural attractions. Salem is also known for its annual Oregon State Fair, which attracts visitors from across the state.