Michigan property owners owe a special tip of the hat to Sault Ste. Marie. Why? Sault Ste. Marie is the northern terminus of the Prime Meridian, which is signified by a monument found by the rail bridge near the International Bridge.
This monument marks the point where the north-south line connects Defiance, Ohio to Sault Ste. Marie. All property descriptions in Michigan are based on this line and an east-west line that runs on the north side of Detroit across to Lake Michigan. The two fundamental lines were established in 1815. The Base Line is at 42 degrees, 26 minutes and 30 seconds, north latitude, and the Prime Meridian is at 84 degrees, 22 minutes and 24 seconds, west longitude. The official survey of Michigan was completed in the Lower Peninsula by 1840, and finished in the Upper Peninsula in 1851.