The northern part of Mississippi was surveyed off the Chickasaw Meridian, whose Initial Point is uncertain, as records conflict about which baseline was actually used. It is possible that the baseline was actually as much as two and a half miles over the state line in Tennessee, due to previous surveying errors in that state (Tennessee, like most of the mid-southern and the northeastern states, was not a Public Land Survey state), though the east/west state line between Mississippi and Tennessee is another possibility. Either way, no monument or marker has ever been found, despite hours of searching in swamps, and no plaques or signage have been erected. This may be the least considered Initial Point in the lower 48 states.
USGS map from 1980 shows the baseline as the state line, though it was established in 1837, four years after the Chickasaw Meridian was established. A parallel line 2.5 miles north, in Tennessee, known as the Winchester Line, was surveyed in 1819, and may also be the line used for the Chickasaw Meridian Initial Point.
The northern portion of Mississippi (in yellow) was surveyed off of the Chickasaw Meridian, the last of a few surveys for the state.