How did the GLO copy plats?

Maybe the river moved? 😉 

There is a table on the plat listing the surveys on which it is based. I often find explanatory notes as well.

We have many townships in the PNW that were partially surveyed, completed, then partially resurveyed. Patents may or may not be issued throughout these activities.

I start by printing all plats, along with field notes. The docs are arranged in date order, starting with the oldest. I review everything in the order it happened. I do the same with patents and deeds, then local survey records. That solves the mystery of multiple plats and keeps me from publishing surveys based on low hanging fruit rather than following footsteps 👣 

Eddie Murray in Missouri was one of my mentors. He walked me through this and wrapped up by saying, If you don't know the order things happened, you don't know what happened. It stuck.

I suppose I could have answered the question...

The various GLO plats I deal with appear to be hand copied, possibly traced. There are variations in the lettering and subsection lines when viewed under high magnification.

I'll go out on a limb and guess they were printed. 

The government was quite a bit more sophisticated than monks in a 12th century monastery 

I find little direct reference to copy methods, but there are some good clues. The 1902 Manuak clearly describes the early triplicate plats as being hand drafted. There is even instruction on how to handle conflicts between 'hand drafted copies'. There is also reference to copies by photolithic process. These are for 'copies provided to applicants'.

I suspect the GLO drifted away from hand copies gradually. You would need the photo or mechanical process to be less labor intensive and expensive than making three copies.

More later, Tom

In Illinois my understanding is they were hand copied.  The originals are available on line.  I once read what the percentage of mistakes were in each copy but don’t recall the number.

I looked through a few more books and see a clear language change in the 1930 manual. They describe the triplicate process as one original and two photolithic copies. It appears the switch happened between the 1902 and 1930 manual. I'll look through my advance sheets to see if there are instructions there.

It's also important to remember there are very few things done exactly the same way at the same time across the country. Different regions had differebt habits, even within a federal agency like the General Land Office. Contract surveyors were 'budget conscious' and certainly provided the triplicate plats in the most economical manner possible.

Comparing plats from the 1880s and earlier I see variations between file, public room copies, and originals. I suspect the photolithographic copies for public distribution started in the mid 1800s, but it was written policy beginning with the 1902 manual.

Well Bill, ya made me look. I have to say I'm incorrect, there are clearly differences on plats from different sources. I've not seen any material issues, such as different measurements, but the text and topo are different. One township I looked at has an 1882 plat from an 1881 survey, it also has a dependent 1945 resurvey. The two 1882 plats are different, while the 1945 plats are identical. 

I've tried twice to make a long post, hit add reply, and it sidn't show up. I'm confused why not.

I have 5 plats of the area of interest, section 2-70-12 5th PM Iowa and nearby. I think I now know better what I have.

--PDF of plat "Duplicate" from BLM site of the township, made from the 1843 survey. It depicts some features including a house, Black Hawk's wigwam, his grave, a field, and a bluff that I believe was a copy error, being a road instead. This survey was rejected.

--PDF of plat "Triplicate" from BLM site of the township, made from the 1843 survey. It shows the same features and has most or all the same acreages. There is at least one crossed out and changed acreage. It has differences in label placement and it has more red and black ink notations.

--PDF of plat "Duplicate" from BLM site of the township, made from the 1846 re-survey. The protracted lots are drawn differently, so acreage can't be directly compared. It shows the road and a much larger field, but no house, wigwam, or grave.

--PDF of plat "Triplicate" from BLM site of the township made from the 1846 survey. It is nearly the same the "Duplicate" but has subtle difference in label placement, number handwriting, etc. Lot 3 acreage is different, and it has a Variation that is missing from the "Duplicate". It has lots of red ink writing including on section 1 as granted to the State of Iowa, which explains why there are no patents on the BLM site for that section - sales would be deeds not involving the Federal government.

--An image of a plat of the immediate area of interest, found on a deceased amateur historian's blog. It shows a little of sections in neighboring townships in other counties, whereas the other plats are exactly one township. It strongly resembles the 1846 "Duplicate" and the lot acreages I've checked match. I has one Variation number that differs. But it has the house, wigwam, and grave that the other 1846 products lack, as if it is a composite.

I'd really like to know where he found the composite image.

I had wondered if they used any mechanical or optical aids to make copies, but after careful comparison I think the copies were made by eye.

@bill93 I've tried twice to make a long post, hit add reply, and it doesn't show up. I'm confused why not

Yep. Same thing happened to me several times. Now I select and copy the post and paste it into Notepad before hitting "reply". Then I can just paste it back into a new post if it disappears.