Apple faces mounting pressure from lawmakers as it prepares to shutter its Towson, Maryland, retail location. The store holds a unique place. It became the first in the company’s U.S. network to unionize. Now, that distinction has drawn scrutiny from nearly 40 members of Congress. The tech giant announced in early April that it would close three stores by late June. Towson Town Center was among them. Company officials pointed to departing retailers and weakening mall conditions. Yet the decision quickly sparked accusations of retaliation. Union leaders saw a pattern. Non-unionized stores slated for closure offered workers transfers. The Towson staff, they claimed, received no such option. The International Association of Machinists and Aerospace Workers, or IAM, filed an unfair labor practice charge with the National Labor Relations Board on April 27. The complaint alleged discrimination against the roughly 90 employees because they had organized.…