Steel Industry National Historic Site Act

Steel Industry National Historic Site Act - Establishes the Steel Industry National Historic Site in Pennsylvania as a unit of the National Park System.

Includes within such Historic Site the following lands: (1) the location of the Battle of Homestead in Munhall, Pennsylvania; (2) the location of the Carrie Furnace complex in Swissvale and Rankin, Pennsylvania; and (3) the location of the Hot Metal Bridge in Rankin and Munhall, Pennsylvania.

Authorizes the Secretary of the Interior to: (1) acquire, by donation only, certain property for inclusion in the Historic Site; (2) enter into a cooperative agreement to further the purposes of the Historic Site; and (3) provide technical assistance for preservation and maintenance of historic structures and the natural and cultural landscape in the Historic Site.

Requires the Secretary to prepare and submit to specified congressional committees a general management plan for the Site.

Grants private property owners protections from public access to private property in the Historic Site.

Authorizes appropriations.