In 1898, the land was sold to the city of Seattle, with plans to build a reservoir and a cemetery.

[1] During World War II, Jefferson Park contained anti-aircraft batteries, and was requisitioned by the U.S. Army for a G.I.

In the post war years, the park returned to normal; the Army structures were mostly removed, though a new Veterans' Administration hospital was built on the site of the original 9-hole golf course.

Jefferson Park received $8 million from the recent ProParks funding levy, allowing redevelopment and remodeling to begin.

Projects in this park revitalization effort include new walking paths, gardens, and a new gymnasium.