The survey itself was performed at the end of the 18th century by Thomas Hutchins, a United States Geographer. In 1781, he was given the title of Geographer of the United States, and was the first and only person to be given it. This led to him being selected and ordered to the Northwest Territory once the Land Ordnance Act of 1785 had passed.
The Land Ordnance Act of 1785 declared that congress could not increase national revenue by raising taxes to U.S. citizens. Instead, they were able to sell the land they had obtained from the 1783 Treaty of Paris.