Fort Atkinson was established as the first U.S. military post west of the Missouri River by the Yellowstone Expedition of 1819, but its story actually Visitor Center The Harold W. Andersen Visitor Center is open daily from May 24th through Sept. 1st from 9 a.m. to 5 p.m. From Sept. 6th through Sept. 28, the visitor center is open Saturdays and Sundays only from 11 a.m. to 4:30 p.m. 2003 Living History Living History Schedule with interpretations from 11 a.m. to 5 p.m. on: May 3rd & 4th May 31st & June 1st July 5th & 6th Aug. 2nd & 3rd Sept. 6th & 7th Oct. 4th & 5th On these days, volunteers portray life at an 1820s military fort. Web site address fortatkinsononline.org For further information, Call (402) 468-5611 or fax at 468-5066. Our e-mail address is email@example.com, or write to Ft. Atkinson SHP, P.O. Box 240, Ft. Calhoun, NE 68023-0240. A valid park permit is required. begins 15 years earlier with the Lewis and Clark Expedition.