In 1817, the northern portion of the Ohio-Indiana border was surveyed and became known as the First Principal Meridian for lands surveyed in the northwest part of Ohio. The 41st parallel north latitude became the base line. Congress Lands lying east of the meridian and south of the base line were first surveyed in 1819 under the direction of Edward Tiffin, Surveyor General of the United States. The tract included Indian reservations surveyed after the tribes ceded the territory. This survey used the six-mile-square township, but townships were numbered sequentially, moving southward away from the baseline. Surveyed ranges were numbered eastward from the First Principal Meridian. The lands South and East of the First Principle Meridian encompass the modern day Ohio counties of Allen, Auglaize, Crawford, Hancock, Van Wert, and Wyandot as well as portions of Hardin, Logan, Marion, Mercer, Morrow, and Putnam counties.
