The John Wanamaker Westchester store at CROSS COUNTY CENTER opened for business in April 1955.
Photo from Library of Congress

Wanamaker's Westchester operation was the first anchor department store to operate at the mall. It was joined by a Gimbels in September 1955.
Photo from Library of Congress

Graphic from John Wanamaker & Company

Another high definition view of the original CROSS COUNTY CENTER. Legible nameplates include F.W. Woolworth, Lerner Shops, Fanny Farmer Candies and Gimbels. The Upper Walk, in the upper left corner of the snapshot, provides the mall with additional retail and office space. 

Photo from Library of Congress / https://www.shorpy.com / Shorpy, The American Historical Photo Archive