The Fifth Principal Meridian was established in 1815 to survey the territory of the Louisiana Purchase, an area of 830,000 square miles. The meridian was then used to survey the land now comprising six states, from North Dakota to Arkansas. The south-ern end of the Meridian started at the confluence of the Arkansas and Mississippi Rivers, and extended northward. The eastern end of the baseline started at the confluence of the St. Francis and Mississippi Rivers and extended westward. Their intersection formed the Initial Point in eastern Arkansas. After its use for the initial surveys, the uncommemorated point was more or less forgotten, until 1921, when surveyors discovered the marked witness trees that surrounded the original point. In 1926 an engraved stone monument was erected. In 1961 the area became the Louisiana Purchase State Park, and a wooden walkway was built a few years later.
When the monument at the Initial Point was installed and dedicated in 1926, the area was dry, but it has since flooded making access difficult. In 1969 an untreated wooden walkway was constructed leading directly to the monument. It rotted out by the late 1970s, and a new boardwalk was constructed.
The currently walkway is 950 feet long, and meanders a bit on the way, providing views of the swamp with interpretive plaques, mostly about flora and fauna.
A perfectly straight line of sight, from the Initial Point through the Tupelo trees, follows the original baseline westward.
The 1926 monument, darkened by the high water mark of the swamp, reads “This stone marks the base established Nov. 10, 1815, from which the lands of the Louisiana Purchase were surveyed by United States engineers. The first survey from this point was made to satisfy the claims of the soldiers of the war of 1812 with land bounties. Erected by the Arkansas Daughters of the American Revolution. Sponsored by the L’Aguille Chapter.”
The contiguous green area shows the region spanning the central part of the nation that was surveyed from the Fifth Principal Meridian, from the Initial Point, where the lines cross in eastern central Arkansas.