Louisiana Purchase State Park

The park commemorates the initial point of the Louisiana Purchase survey, established in 1815 by U.S. Deputy Surveyor Prospect K. Robbins and his crew. They set a post at the intersection of the baseline (the 33rd parallel north) and the Fifth Principal Meridian, which became the reference for all public land surveys in the territory. The site was largely forgotten until the 1920s when surveyors rediscovered it, and in 1961 the Arkansas General Assembly designated it a state park. The monument, a granite shaft, was erected in 1926 by the Louisiana Purchase Survey Association.¹

The park lies in the Mississippi Alluvial Plain, characterized by bottomland hardwood forest and swamp. A 1.5-mile boardwalk leads visitors through a cypress-tupelo swamp to the monument, which stands on a small rise. The boardwalk is elevated to protect the wetland and offers interpretive signs about the ecosystem. The park also includes a picnic area and a small pavilion. The initial point itself is marked by a brass cap set in concrete, surrounded by a granite post.²

The initial point is the origin for the rectangular survey system used to divide the Louisiana Purchase into townships and sections. Robbins and his crew used astronomical observations to determine the latitude and longitude, and their work enabled the sale and settlement of land in present-day Arkansas, Missouri, Iowa, and other states. The Fifth Principal Meridian runs north from the point, and the baseline runs east and west. This system, later extended across the American West, is a foundational element of U.S. public land policy.

Visitors can walk the boardwalk, birdwatch, and enjoy the park's quiet natural setting. The park is a popular destination for school groups learning about the Louisiana Purchase and surveying history. Interpretive panels along the boardwalk explain the survey process and the significance of the initial point. The park also hosts occasional special events, such as commemorations of the Louisiana Purchase anniversary. There is no entrance fee, and the park is open year-round during daylight hours.³

One lesser-known fact is that the initial point was originally marked by a small wooden post, which was later replaced by a stone marker in 1881. The 1926 granite monument was placed after a campaign by the Arkansas Daughters of the American Revolution. The park is also a stop on the Arkansas Delta Byways and is part of the Mississippi River Trail. Additionally, the swamp is home to the rare American alligator, and visitors occasionally spot them near the boardwalk. The park's remote location means it is often uncrowded, offering a peaceful experience.

Initial point

The reference point for land surveys, where a baseline and principal meridian intersect.

Baseline

An east-west line used in the Public Land Survey System.

Principal meridian

A north-south line used in the Public Land Survey System.

Township

A square unit of land, typically six miles on a side, used in the survey system.