Contracts & Grants Emergency Management & Public Info. General Services Human Resources County Commission Employment Contact	Contacting the Department of Administration Mailing Address: PO Box 100 Hillsboro, MO 63050 Phone: (636) 797-5071 Email: mabel@jeffcomo.org Office hours: 8:00am - 5:00pm Monday - Friday Physical Address: Department of Administration 729 Maple Hillsboro, MO. 63050 Official Holidays: New Year's Day (Jan. 1) Martin Luther King Day (3rd Mon. of Jan.) Lincoln's Birthday (Feb. 12) President's Day (3rd Mon. of Feb.) Truman's Birthday (May 8) Memorial Day (last Mon. in May) Independence Day (July 4) Labor Day (1st Mon. in Sept.) Columbus Day (2nd Mon. in Oct.) Veteran's Day (Nov. 11) Thanksgiving Day (4th Thur. in Nov.) Thanksgiving Friday (4th Fri. in Nov.) Christmas Day (Dec. 25) Key Contact Copyright © 1999-2000 Jefferson County, Missouri All rights reserved.