EXHIBIT 21 SUBSIDIARIES OF UNITED BANKSHARES, INC. United National Bank (subsidiary of second-tier bank holding company, UBC Holding Company, Inc., a wholly-owned subsidiary of UBS) United National Bank - South Bank First, N.A. (subsidiary of second-tier bank holding company, UBF Holding Company, Inc., a wholly-owned subsidiary of UBS) United Venture Fund, Inc. Commercial Interim Bank (formed to facilitate the acquisition of First Commercial Bank, Arlington, Virginia) United Mortgage Company, Inc.