The area we now know as the state of Missouri wasn't part of the United States until the Louisiana Purchase in 1804. French and other settlers who moved into the area in the 1700s received grants of land from the colonial government of the time, whether Spanish or French.
A land survey was part of the process of obtaining a legal title. Surveys done prior to 1804 used a unit of measure called arpents instead of acres. Using a grid system was not required.
After the Louisiana Purchase, residents wanted to know if their claims to land would remain valid. The US government set up a board of land commissioners that took more than 50 years to review all the claims, by which time many of the original claimants were deceased.
This detail of a page from the 1898 plat book of Jefferson County shows the contrast between the square grids used by the US government and the irregular shapes of earlier land surveys. A glimpse of Kimmswick and the Mississippi River can be seen at the lower right.
In the pink section on the left, Seckman (which had a post office) appears in Section 2. This section is part of a square grid system of townships and ranges that the United States used in Missouri and other states to survey public lands.
The parcel labeled Survey 2970 crosses sections 2, 3, 10, and 11 at a diagonal. It doesn't fit the grid—a clue that it's a parcel of land surveyed under the French and Spanish colonial governments, before Missouri became part of the United States.