Blog · October 14, 2026 · South Dakota
Union County Plat Book: finding and using one
Out toward North Sioux City, plat books show ownership by township; the parcel viewer shows it today.
Main page: Union County, SD GIS & Parcel Viewer (official map link, county facts and neighboring maps).
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Looking for a Union County plat book? It's a printed atlas of landownership, usually by township, and it's handy for land around Missouri National Recreational River. This Union County guide covers: what's in a plat book, where to find editions, and the free online map that stays current.
Getting started with the Union County plat book
With a lot near Dakota Dunes, a plat book is a privately published atlas, showing rural owners and tract lines, usually township by township.
Pulling up a parcel
The official parcel map for this area is the Union County Beacon site, and it opens in a browser with no account. In and around Missouri National Recreational River, put in a street address, an owner's name or a parcel number, and the viewer zooms to the match. In and around Jefferson, save the parcel ID from that panel; every clerk in the county uses it to find the file.
A quick look at the area
Elk Point serves as the county seat, where most land records are kept. Other places on the map include Alcester, Beresford, Jefferson, and North Sioux City, where town lots give way to larger tracts. Roughly 17,183 people call Union County home (Census Bureau estimate, 2023) spread over some 461 square miles. The county was organized in 1862, which matters when you trace an old farm's title, at least around Beresford. Features like Big Sioux River, Missouri River, and Adams Homestead and Nature Preserve help you orient on the aerial.
Field tips
The parcel map usually runs in a mobile browser, handy when you're parked on a road near Elk Point, though signal can drop in rural spots. A printout of the tract near Alcester helps when you meet an owner or agent.
Making your own township pages
Screenshot each section of the viewer around Jefferson and keep them in a binder for the truck.
Who handles what
Recorded documents for a parcel near Dakota Dunes sit in the index kept by the Register of Deeds, sometimes only in person. Building or septic questions for a lot near Missouri National Recreational River need the planning or permitting office, town or county, depending on location.
Limits of the parcel data
For land near Beresford, listed acreage is an estimate; only a licensed surveyor sets the real boundary on the ground. On ground around Missouri National Recreational River, owner names and values update on a schedule, so a deed recorded last month might lag behind.
Why people still buy them
Buyers and seed dealers around Elk Point rely on them for a big-picture view of who owns what.
When a parcel crosses a boundary
Union County meets Plymouth County, IA, Sioux County, IA, Woodbury County, IA, Dakota County, NE, and Dixon County, NE, all with their own assessor records. Ground near Missouri National Recreational River that runs to the line can show up in two county records, so look at the adjacent map as well. Out toward Big Sioux River, our state page links each neighboring county map across South Dakota.
Buying or borrowing a copy
Older editions near North Sioux City turn up in libraries and historical societies, which helps when tracing a farm's history.
Backing up the map with records
For acreage around Beresford, the map is an index, not the title: deeds, plats and easements for parcels in the county are kept by the Register of Deeds. Near Missouri National Recreational River, have ready the book and page from the tax record and the lookup takes minutes.
Current ownership online
Between printed editions, the Union County Beacon site shows current owners, including rural land around Elk Point.
Plat book vs. recorded plat
Out toward North Sioux City, don't confuse the atlas with a recorded subdivision plat: the recorded plat at the Register of Deeds is a legal document, while the atlas is a reference.
Reading the legal description
South Dakota uses the Public Land Survey System, which means a tract near Richland is described by section, township and range. Each section is nominally a mile square, about 640 acres, and a township holds 36 of them, though real sections near Dakota Dunes vary in size. Copy the legal description from the record for the parcel near Dakota Dunes when you talk to a surveyor.
Quick answers
Are plat book lines exact near Dakota Dunes?
For land near Missouri National Recreational River, the deed and a survey decide; don't rely on them for boundaries.
Can I use a plat book for a boundary near Elk Point?
For acreage around North Sioux City, a plat book is a privately published atlas; check the deed.
Plat book or parcel viewer for land near Beresford?
Usually, the Union County Beacon site is free and updated more often.
How do I research old landowners near Dakota Dunes?
For a parcel near Dakota Dunes, some older atlases have been digitized; availability varies.
Is the parcel map a survey around Alcester?
For property near Richland, parcel lines are tax drawings, not surveys.
Open the official Union County, SD parcel map See it in the Platbookmapper directory
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, especially for fences, setbacks, or boundary disputes.