Originally known as the Haines Mission, the Fort William H. Seward is a military installation in Haines, Alaska built during the gold rush era. It is actually one of the last 11 posts built in the area during the time.

The Fort William H. Seward was completed in 1902, in compliance with the 1898 Executive Order. It was founded so there would be governmental forces in the area that could help maintain peace and order among the folks who trooped to the site to get some gold. It also provided US military presence during the time when the issues about the boundary disputes with Canada were ongoing.

Today, the Fort William H. Seward is a National Historic District valued for its contributions to the area.