The idea of changing the name of Whitman National Monument was not new. Custodian Tom Garth favored "Whitman National Historic Park" while Superintendent Robert Weldon thought "Memorial Obelisk" better described the monument shaft on the hill. After Historian Erwin Thompson proposed the designation "National Historic Site" in the 1960s, the Marcus Whitman Foundation pressed that change to fruition.

In November 1961, Allen Reynolds, representing the Marcus Whitman Foundation, requested that Senators Magnuson and Jackson introduce a bill in Congress to change the name of the Whitman National Monument to the Whitman Mission National Historic Site. The change was recommended, with the full support of the National Park Service, because it would be "more descriptive and less confusing." [21] The name change clarified that the Whitman Mission was not a monument, but a historic site, commemorating a mission and not a memorial shaft.

On January 18, 1962, Senators Magnuson and Jackson introduced S. 2705, and Representative Catherine May introduced an identical bill, H. R. 9805, on January 22. The bill, after being approved by the Committee on Interior and Insular Affairs, passed the House on March 28, following the same procedure in the Senate, passing May 17. President John F. Kennedy signed H. R. 9805 on May 31, 1962, with the name change going into effect January 1, 1963. (Public Law 87-471, 76 Stat. 90)

The Marcus Whitman Foundation deserves full credit for initiating this project, appropriately timed before the National Park Service constructed new signs and markers for the Whitman Mission grounds. The Whitman Mission is clearly and logically described today as the Whitman Mission National Historic Site.