The Board of Selectmen has canceled the special election that was scheduled for Sept. 21. The election was for a referendum on whether Tewksbury supported the proposal by Penn National Gaming to develop a slot machine parlor on 30 acres off Route 133. The vote was canceled after Town Meeting on Aug. 20 rejected proposed zoning changes needed for Penn to carry out the development, according to Town Manager Richard Montuori. Penn needed approval of the zoning changes and a positive vote in the special election to proceed with its bid for a state license for the facility. With the defeat of the zoning plan, the company could not move forward in Tewksbury, so the referendum was no longer needed.