Gladstone is a city located in Clackamas County, Oregon, United States. The population was 11,491 at the 2010 census. Gladstone is an approximately 4-square-mile suburban community, 12 miles south of Portland, the largest city in Oregon, and located at the confluence of the Clackamas and Willamette rivers.Gladstone has held several important cultural and social events, hosting both the inaugural Clackamas County Fair and the Oregon State Fair, before both were moved to more spacious locations. Both Secretary of State William Jennings Bryan and presidential candidate Theodore Roosevelt have given public speeches in the city.