Cherry Hill Street was the northern limit of the village of Dearborn until 1925. Once the community expanded, Ford Road became the northern boundary of the village and the modern west side. As the west bound lanes are the original portion of Ford Road, the boundary follows the middle of those lanes.
Since 1963, Dearborn west of the Rouge has bordered Dearborn Heights on the north side. That portion of Dearborn Heights was previously an area of Dearborn Township that was never annexed by Dearborn.
East of the Rouge, the northern boundary of Dearborn juts north of Ford Road briefly along the northern edge of Private claim 317 and 318. Those private claims are the boundary of an old 1790s French style ribbon farm. Starting in the 1820s, that property was owned by the Ten Eyck family. In the early 1900s, that land was acquired by Henry Ford. The northern bit of the property north of Ford Road was donated after Henry Ford’s death to be used for churches and religious buildings. Altar Road runs through that area today.
In 1925 Detroit annexed a large portion of Dearborn Township and Redford Township so what is now Rouge Park could be included in that city. News coverage in the Detroit Free Press mentions that Henry Ford’s land holdings limited how far south that annexation went. As a result, the northern portion of Dearborn Heights south of Rouge Park and Dearborn in the Fair Lane area west of Greenfield were not annexed by Detroit due to the influence of Henry Ford.
While the northern border of Dearborn is defined by old Henry Ford land holdings in the central portion of the city, it follows an old township border out east. The city of Fordson which merged with Dearborn in 1929 consisted of the remainder of Springwells Township not annexed by Detroit. Tireman Avenue, which is the northern border of Eastern Dearborn, follows the old north border of Springwells Township.