Why is a national bank unconstitutional?

21ST CENTURY Bank 7 Bank of Magnolia Company 13 Bank of Milan 11 Century Bank & Trust 6 Covington County Bank 1 Eastern Michigan Bank 4 Farmers & Merchants Bank of St. Clair 1 First Cahawba Bank 8 First Midwest Bank of Dexter 10 Gulf Coast Bank 12 Iowa Trust & Savings Bank 5 LEA CTY State Bank 8 Lincoln State Bank 12 MINNWEST Bank 12 Ohio Valley Bank Company 12 Philadelphia Trust Company 16 Saint Martin National Bank 4 Sherwood Community Bank 2 St. Henry Bank 12 Wolf River Community Bank 6