The Twentieth Century brought massive change to Arkansas Post. In the opening years of the century, the
1900 An article printed in the December 2 issue of the Arkansas Gazette details the condition of the town site area in Arkansas Post.
The course of the Arkansas River changed, cutting off the bend along which the Post was located.
1923 Mrs. G.G. Lewis, president of the Arkansas Authors' and Composers' Society first suggests that some sort of memorial be placed at Arkansas Post.
1926 The November 11 issue of the Arkansas Gazette carries an article by columnist Fletcher Chenault which details the significance of the site. Chenault calls Arkansas Post "the shrine that Arkansas forgot."
1927 Major flooding along the Mississippi and Arkansas Rivers.
1929 State representative Ballard Deane sponsors a bill to establish a State Park at Arkansas Post. A State Park Commission consisting of twelve members were placed in charge of the park.
February 27Arkansas Post State Park signed into law by Governor Harvey Parnell.
1930 June 17 F. J Quandt donates 20 acres of land for the new state park. An "old-fashioned picnic" was held to celebrate the occasion.
1931 February 20 The state legislature appropriates $5,000 to beautify and develop the Arkansas Post State Park.
March - NovemberLandscape Architect P.C. Howson supervised the development of the new park. This initial work included: a fence to enclose the park; construction of a care-taker's lodge; restoration and stabilization of the well and cistern in the town site; construction of a picnic area; the ravine was dammed, creating a seven-acre pond; landscaping; and the statue of justice was placed on a pedestal by the lake. This work ends in November when the $5,000 had run out.
Two additional tracts of land were acquired; bringing the size of the park to 40 acres.
1932 – 34
Little development occurs at the park, due to a lack of funds.
1934 The WPA conducts a project at the park, assisting in cleaning, landscaping, and beautifying the park.
1935 January 23 Control over the Arkansas Post State park passed from the Arkansas Post State Park Commission to the Arkansas State Park Commission.
March 30 The National Park Service issues a summary of the historical significance of Arkansas Post.
1939 June The National Park Service conducts a review of the Arkansas Post State Park for possible inclusion in the National Park system.
1940 The park had grown to 62 acres in size.
By this time four overnight cabins had been built along the park lake.
March 28The National Advisory Board of the National Park Service recommends that Arkansas Post be classified as an eligible site for inclusion in the National Park system.
1940s World War II disrupts park planning.
1950 Archeological field work occurs at the Menard mounds site.
1956 Congress appropriates $32,000 for archeological investigations in the Arkansas Post area. This money funds historical research and archeological field work for 1957.
Archeological field work begins at the Menard mounds site, as well as at the Arkansas Post State Park.
1957 Congress appropriates an additional $15,000 to continue research work towards locating the different sites of Arkansas Post in 1958.
A series of historical reports and resource material on Arkansas Post is completed by NPS historian Ray Mattison.
Archeological field work continues at the Menard mounds site and on the grounds of the Arkansas Post State Park.
1959 March 26 Congressman W.F. Norrell introduces a bill to establish Arkansas Post as a unit of the National Park system.
1960 July 6Public Law 86-595, establishing Arkansas Post National Memorial, is signed by President Eisenhower.
1964 June 23 In a formal ceremony, Governor Orval Faubus presented the deed to the area to the National Park Service.
September 28The National Park Service assumes operations at Arkansas Post.
1965 Construction began on rerouting State Highway 169 to the north end of the park, including a new bridge over Post Bayou. The new road opened to the public on June 30, 1965.
1966 NPS archeologist Rex Wilson supervises extensive field work in the town site area.
Congressman Wilbur Mills sponsored a bill to raise the development ceiling of the park. The bill was signed into law on August 11.
1967 August A new Visitor Center opened near the entrance to the park. Originally intended as a maintenance office, it would serve as the visitor center until 1981.
October The log house built in 1931 as a Caretaker's cabin is moved from the park to the nearby county museum.
1969 March 2The sesquicentennial of the Arkansas Territory was commemorated in a special program at the park; over 4,000 visitors took part in the event.
1970 NPS archeologist Rex Wilson excavates the site of the State Bank building. This remains the best documented historic structure in the town site area.
1971 The University of Arkansas holds its field school at Arkansas Post, with the intention of locating the remains of Montgomery's Tavern.
A report on the excavation of the State Bank Building is published.
NPS Historian Ed Bearrs completes two reports on Arkansas Post: A historic structure report on the Montgomery's Tavern site, and a structural history of Arkansas Post, including base maps of the town site and the Civil War battlefield.
1974 February 28 The Arkansas Society, DAR donates $15,000 to the National Park Service to commemorate the Colbert Raid, Arkansas' only Revolutionary War battle, which occurred at the Post in 1783.
NPS Historian Ed Bearrs completes a Special History Report on the Colbert Raid.
1976 During the spring, the DAR exhibit commemorating the Colbert Raid is completed.
Bicentennial programs bring upwards of 10,000 people to Arkansas Post for the fourth of July.
1979 August Work begins on the new Visitor Center building.
1981 January 13 The Visitor Center building is completed.
June Trail system marking roads in the old town site area is completed.
July Wayside exhibits in the town site and at the rifle pits were installed.
August Visitor center exhibits and orientation film installed.
October 3 Official opening of the new visitor center.
1997 Legislation authorizing the Osotouy unit passed by Congress
2000 Osotouy unit established.
2003 A yearlong commemoration of the Louisiana Purchase bicentennial brings visitors to the park.
April The park orientation film, "Arkansas Post Revisited," is retired after 22 years, and replaced by the film "Arkansas Post: Echoes of the Past."
2010 The park celebrates 50 years in the National Park Service