Blog · September 30, 2026
What Is Single Proportionate Measurement?
Single proportionate measurement restores a lost corner on a line between two recovered corners. It keeps the original survey’s relative distances along that line. It is a restoration rule, not a way to average your fence into the deed.
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The idea in plain numbers
Suppose an original mile was chained as two half-miles of 40 chains each, and the quarter corner monument is lost. The two section corners are found, and the measured mile between them is a little long or a little short of 80 chains. Single proportion puts the quarter corner back on that line so each half keeps its share of the original ratio. You do not simply mark the modern midpoint unless the original record distances were equal. If the record showed 39 chains on one side and 41 on the other, the restored point honors that uneven split, scaled to the distance you can measure today between the recovered ends. The arithmetic is simple. Knowing that the ends are the right corners is the hard part.
Where the rule applies
Single proportion is the usual method for a lost quarter-section corner on the line between two found section corners, and for some other lost corners that the survey instructions place by one-direction proportion. It is not the method for a lost corner common to four sections, which generally wants double proportion. It is not the method for a platted subdivision lot. If your question is a missing iron on Lot 12, you are in a different restoration problem. Read the kind of corner the note is about before you borrow the formula. A county GIS measure tool reports its own map distance, which is neither the original chainage nor a proportion.
What a landowner should leave alone
Do not run a measuring wheel between two pipes and drive a stake at the split. Even if the formula is right, the pipes have to be the controlling corners, the line between them has to be the right line, and existing evidence of the lost corner has to be absent. A wheel and a laser measure are not a survey. Setting a stake can be mistaken later for a monument. If a filed survey says a quarter corner was restored by single proportion, read which corners were held and what record lengths were used. That sentence is the opinion. Your sketch is homework, not a new corner.
What to do next
- Identify the two recovered corners the method holds.
- Copy the original record distance on each side of the lost point.
- Note the kind of corner, so you do not use single proportion where double proportion is required.
- Leave the staking to a surveyor.
The mix-up to avoid
Always splitting the measured line in half. Equal splits are right only when the record distances were equal. Many lines were not chained that way, and half is then the wrong place.
Questions people ask
Does single proportion ignore monuments in between?
If a reliable monument or accessory still exists, the corner is generally not treated as lost, and proportion does not start. Proportion is for the case where that evidence is gone. Found evidence in the middle changes the problem.
Will the parcel map show the proportioned point?
No. The assessment map is drawn for tax parcels. It does not store the record chainages or the restored coordinate unless some local layer happens to plot a survey, which you still verify against the filed plat.
Find the county map
Open Platbookmapper and pick the county that taxes the land. Use that viewer to get the parcel id, then match it to the recorded plat if you need the easements and lot numbers.
Not a survey. County GIS and tax parcel maps are assessment and planning layers. They are not a substitute for a recorded plat, deed, or licensed survey.