Blog · September 30, 2026
What Is a Lost Corner?
A lost corner is a public-land or other survey corner whose monument is gone and whose position cannot be recovered from reliable evidence. It is restored by proportionate measurement from other corners, not by guessing where the fence looks oldest.
Platbookmapper is an Amazon Associate. If you buy through an Amazon link on this page, we earn a commission. The link is a product, not the county map.
A term with a threshold
Lost is not a casual word for I cannot find the pin this afternoon. In the public-land system, a corner is treated as lost only after the search shows that the monument and its accessories are gone and that no acceptable evidence remains of where the corner stood. Until that threshold is met, the corner may be obliterated rather than lost, and local evidence controls. The distinction changes the method. Lost corners on section lines are restored by proportion so that the record measurements of the original survey are honored in ratio. That math is not the same as splitting the difference between two fence posts.
What the proportion is doing
Single proportion restores a corner that sits on a line between two recovered corners, placing it so the relative record distances are kept. Double proportion is used for many lost section corners and compares distances in both directions. The method belongs to corners of the government survey. It is not a home method for sliding a subdivision lot corner because the iron is missing. Lot corners in a simultaneous plat are restored from the plat, from surviving lot corners, and from the rules for that kind of survey. Using section-corner proportion on a city lot will invent a corner the subdivision surveyor did not set.
Why the tax map stays out of it
A parcel viewer has no opinion on whether a corner is lost. Its line is a general boundary for assessment, often digitized from older maps, and it can sit several feet from any monument. You cannot restore a lost corner by clicking the GIS vertex. Platbookmapper links to that viewer so you can find the parcel page. It does not compute proportion, and it does not cover non-U.S. cadastral systems. If a survey narrative says a section corner was lost and restored by double proportion, read the corners that were held and the record distances that were used. Those inputs are the restoration. A laser measure between two pipes you hope are original is not those inputs.
What to do next
- Use the word lost only when the notes say the corner could not be recovered.
- Read whether the restoration was single or double proportion.
- Write down which recovered corners were held.
- Do not proportion a platted lot corner with a phone app.
The mix-up to avoid
Declaring a corner lost after one walk through the woods. A short search misses bearing trees and buried stones. Proportion applied too early moves a corner that evidence could still have fixed.
Questions people ask
Is a lost corner the same as a missing lot pin?
No. Lost corner is a restoration category, mostly discussed for government survey corners. A missing lot pin may be easy to reset from the other pins of the same plat. Different evidence, different method.
Can proportion give me more acreage than the deed?
Proportion restores a corner. It does not rewrite the grant. Any area that results is a consequence of where the original survey placed the lines, including its excess or deficiency. It is not a bonus the calculator awards.
Find the county map
Search the county on the Platbookmapper home page. The directory links to the official parcel viewer. It does not draw the lots, and the line on the screen is an assessment map, not a survey.
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.