Gladstone is a city located in Clackamas County, Oregon, United States. The population was 11,491 at the 2010 census. Take a look below for 20 awesome and interesting facts about Gladstone, Oregon, United States. 1. Gladstone is an approximately 4-square-mile (10 km2) suburban community, 12 miles (19 km) south of Portland, the largest city in…