First, even open rangeland is not so featureless at 4 mph as it is at 70 mph. When the lives of your family and your animals depend on finding water or taking shelter, you'll quickly develop an understanding of where to look for a ravine or spring, where to shelter from a wind or dust storm, which way to the railroad or nearest town.

Second, it would be pretty unusual to journey into unknown country looking for a specific parcel. In nearly all cases, settlers inspected the available land before deciding to make a claim on a specific parcel. The earliest settlers sometimes claimed and improved land before Congress had officially authorized its survey and sale, and there were techniques for recording preemption claims. Later settlers came with the encouragement of railroad companies selling off their land grants, or were able to hire local experts who knew the available land. Often these were the same men who'd walked the townships to survey it, recording (as instructed) all roads, trails, watercourses, swamps and depressions, bluffs, timber stands, and the like. Here, for instance, is the surveyor's plat of a township southwest of Chicago. As they systematically walked the land, setting corner markers at one-mile intervals, the surveying parties both recorded and made mental notes about the most promising sites. The plats of the lands to be sold showed many of these features, so that a new arrival looking over the plat books in the regional land office could make some educated guesses about parcels to be further inspected.

In the rare instance of someone arriving with just a land description of a parcel they'd somehow come into possession of, they'd know (or could easily look up) what county it was in and what was the nearest railroad depot. They could study and copy the plat maps in the regional land office. Published county maps showing at least section lines, streams, and roads often would be found hanging in banks, hotels, courthouses, and even general stores. When you went out to look for your land, there should have been official markers at the section corners, and the midpoints (quarter-section corners) as well. At first, these were wooden posts or mounds of stones or dirt. Later, stone posts marked with numbers were set, and in the 20th century surveyors switched to less expensive, easier-to-transport iron pipes. To help find these corner markers, in forested areas, corners might be marked by blazing (stripping bark from) witness trees. In treeless prairie, surveyors were instructed to mound up dirt around the corner marker, using dirt dug from pits a few feet away. The different, greener, vegetation that would grow from those pits would, for much of the summer, stand out and thus guide you to the corners when looking across an endless golden grassland. In areas valuable enough to fence and farm, it was not uncommon to have the corners resurveyed and more prominent markers installed within a few years of claiming a farm.

The North American scheme of rectangular land surveying also gave us section-line roads, the practice of dedicating a right of way 66 feet wide (33 feet taken from the adjacent land on both sides) along all section lines as a public road. Of course, few of these roads were improved prior to the 20th century, but many High Plains states made all their section lines public roads, giving a statewide gridded framework that made it easy to seek out monumented section corners and find specific parcels.

One of the few books I've found on this unique yet ubiquitous American landscape and how it came to be is Hildegard Binder Johnson's Order Upon the Land, which focuses mostly on the Upper Mississippi Hill Country, a large region centered around Dubuque. Bill Hubbard Jr.’s 2008 book American Boundaries: The Nation, the States, the Rectangular Survey gives a superb history of the Public Land Survey System and how it spread across the West, as well as its influence on county and even state boundaries.

Textbooks on surveying describe how the PLSS was done and monumented in instructive detail. I had hoped to find J.B. Cleary’s United States Land Surveys, a 1936 textbook I own, at Google Books or Internet Archive—but no such luck. It’s cheap and easy to find from various used book sources, though.