This map shows the land six miles deep on each side of the Grand River, from Lake Erie to the river’s head, as the Mohawk Nation of Grand River has determined it.
About this map
Why it exists
By the Proclamation of 25 October 1784, the Crown set these lands apart for the Mohawks and their posterity: “six miles deep from each side of the river beginning at Lake Erie and extending in that proportion to the head of the said river.” This map is the Nation’s own drawing of that line.
The Nation needs to know where its land lies to do its daily work: to place a resident’s home, a parcel or a permit, to see where land is being built on or sold, and to answer plainly when asked. Its maps are drawn from the record, not from anyone else’s view of it.
How it was made
The line runs six statute miles — 9,656.064 m — out from the edge of the river’s water, measured on the ground, along both banks. It was checked at 4,000 points and lies within two metres of six miles everywhere. The river is drawn from the Grand River Conservation Authority’s mapping; nothing was redrawn by hand.
How sure it is
Every stretch of the line carries a grade, and the map draws each differently, so certainty can be seen at a glance. Where an old surveyed limit runs alongside, the stretch is corroborated (85 km, solid green). Where it is measured from the mapped water, it is measured (313 km, solid navy). Through Belwood Lake, where the river’s natural banks lie under a reservoir, it is measured from the river’s own flow line, and drawn dashed. At Lake Erie and beyond the head of the river, it depends on how the Proclamation’s ends are read, and is interpreted (dotted).
All of it is set out in the Certificate of Determination below, with the data anyone can check.
How it can be vetted further
A map like this is made stronger by being tested. The Nation is seeking:
- The original surveys. The plans and field notes of the townships along the river, which show the lines the surveyors actually ran. Where they place a limit at six miles, that stretch is confirmed.
- A check on the ground. An Ontario Land Surveyor can locate surviving survey monuments and measure them against the line.
- Outside review. The method is being put to the Surveyor General of Canada for comment on the standard to apply; an independent recomputation by a university or other surveyors is welcome.
- The original river data. The river polygons will be compared point by point with the Authority’s original Waterbody download, and the reading of the two ends decided.
You can help. If you hold old survey plans, deeds, maps or photographs of the river and its lands — or your family knows where the line was understood to run — please bring them to the Secretariat. Each one is recorded, with credit, and weighed with the rest.
The map
Encroachments on the public record Parcels under determination — beneath them, the six miles as the Nation has determined them.
The certificate
The six miles shown above are certified in Certificate of Determination TDC001-261021-000002, issued 21 October 2026. It sets out the measure, how the line was drawn, how it was checked, the evidence of the old surveys, the grade of every stretch, and what remains open.
466 km
the six-mile line, all the way round
4,582 km²
within the six miles
±2 m
from six statute miles, checked on the ground at 4,000 points
85 km
agreeing with the old surveyed limits
The poster
The map as a poster, 24 × 36 inches. It is printed from the Register, so it always carries the certificate, the publication number and the ISBN in force.
The six miles, on Grand River navy
Open it — then print or save as PDF · the printer’s file
For a print shop, each poster’s printer’s file carries 3 mm bleed and crop marks. Ask them to convert it to PDF/X before printing.
How to validate it
You need not take the Nation’s word for it. Anyone can check the six miles themselves.
- Download the certified data. graded.geojson — the river, the six-mile line with its grades, the evidence, and the full record of how it was made, as GeoJSON.
- Check that it is the data certified. Its fingerprint (SHA-256) must be exactly:
7b572f7097012b7d59afdfd1e543034e61aa3088c00a3126ea85e99295d63a6bTo work it out on your own computer:Windows (PowerShell): Get-FileHash graded.geojson -Algorithm SHA256 Mac: shasum -a 256 graded.geojson Linux: sha256sum graded.geojson
If one character of the file were changed, the fingerprint would be entirely different. - Recompute the line. Six statute miles are 6 × 5,280 feet × 0.3048 m = 9,656.064 m. Measure that distance, on the ground, outward from every point of the water’s edge in the data. The certificate gives the projection (NAD83 / UTM zone 17N), the grid distance that equals six miles on the ground (9,652.818 m), and the result to compare against: every point of the line within −1.5 to +2.1 m of six miles.
- Check any place. Tap the map, or use “Am I inside the six miles?”. Software can ask the same question here:
https://mohawkuniversity.org/Register/api/mngr/v1/open/sixmiles?lat=43.1390&lng=-80.2644— it answers inside or outside, whether the place is in the riparian zone, the distance to the line, and the certificate it rests on. - Check the evidence against the original surveys. The plans and field notes of the townships along the river, held by the Archives of Ontario and the Office of the Surveyor General of Ontario, record the lines the surveyors actually ran. Where they place a limit six miles from the river, that stretch is confirmed.
- Check it on the ground. An Ontario Land Surveyor can locate surviving survey monuments along those limits by GNSS and compare them with this line and with the original notes.
- Have the method reviewed. The method is being put to the Surveyor General of Canada for technical comment, on the standard the Branch would apply.
Produced using information under licence with the Grand River Conservation Authority. © Grand River Conservation Authority, 2026. Contains information licensed under the Open Government Licence – Ontario. © King’s Printer for Ontario, 2026. © Mohawk Nation of Grand River Secretariat, 2026. All rights reserved. MPN001-000001-000397. ISBN 978-1-0680559-2-8.
