The bidding date, originally December 20, 1961, was postponed to January 22, 1962, to clarify the details of the arch construction. About 50 companies that had requested the construction requirements received bidding invitations. Extending from $11,923,163 to $12,765,078, all four bids exceeded the engineer estimate of $8,067,000. Wirth had a committee led by George B. Hartzog Jr. determine the validity of the bids in light of the governments conditions. Following a meeting with the bidders, the committee affirmed the bids reasonableness, and Wirth awarded the lowest bidder, MacDonald Construction Co. of St. Louis, the contract for the construction of the arch and the visitor center. On March 14, 1962, he signed the contract and received from Tucker $2,500,000, the citys subsidy for the phase. MacDonald reduced its bid $500,000 to $11,442,418. The Pittsburgh-Des Moines Steel Company served as the subcontractor for the shell of the arch.. How many more dollars was the lower estimate from the engineer estimate?