Platbookmapper County GIS Directory

County GIS · State lines · October 19, 2026

Illinois–Missouri Border Counties: Parcel Maps on Both Sides

All 27 counties on the Illinois–Missouri line, with seats, 2023 populations and a link to each official parcel map, plus what changes at the state line.

Looking for the counties on the Illinois–Missouri border and their parcel maps? According to the Census Bureau's county adjacency file, 12 Illinois counties touch 14 Missouri counties and 1 independent city along the line. Each one keeps its own property records and its own parcel viewer, so land near the line often means checking two counties in two states.

A farm, hunting tract or lake lot can sit in one state while the road, the neighbors or the rest of the property are in the other. This page lists every county that touches the line on either side, with links to each official parcel map.

Illinois–Missouri border at a glance

Illinois counties on the line

County Seat Land (sq mi) 2023 pop. Parcel viewer
Adams County Quincy 855 64,441 ArcGIS Map Viewer
Alexander County Cairo 235 4,695 ArcGIS Map Viewer
Calhoun County Hardin 254 4,317 county web map
Hancock County Carthage 794 17,186 ArcGIS Experience Builder
Jackson County Murphysboro 584 52,141 BHA Maps
Jersey County Jerseyville 370 21,091 ArcGIS Experience Builder
Madison County Edwardsville 716 262,752 county web map
Monroe County Waterloo 385 34,957 ArcGIS Web AppBuilder
Pike County Pittsfield 831 14,342 WTH GIS
Randolph County Chester 575 29,815 ArcGIS Web AppBuilder
St. Clair County Belleville 658 251,018 county web map
Union County Jonesboro 413 16,667 no verified public viewer listed yet

Missouri counties on the line

County Seat Land (sq mi) 2023 pop. Parcel viewer
Cape Girardeau County Jackson 579 82,984 CAMAvision Maps
City of St. Louis — 62 281,754 ArcGIS Map Viewer
Clark County Kahoka 505 6,641 CAMAvision Maps
Jefferson County Hillsboro 656 231,230 ArcGIS Experience Builder
Lewis County Monticello 505 9,818 CAMAvision Maps
Lincoln County Troy 627 64,699 CAMAvision Maps
Marion County Palmyra 437 28,336 CAMAvision Maps
Mississippi County Charleston 412 11,822 IntegrityGIS
Perry County Perryville 474 18,950 CAMAvision Maps
Pike County Bowling Green 670 17,935 CAMAvision Maps
Ralls County New London 470 10,489 IntegrityGIS
Scott County Benton 420 37,889 BreezeMaps
St. Charles County St. Charles 561 416,659 county web map
St. Louis County Clayton 508 987,059 ArcGIS Experience Builder
Ste. Genevieve County Ste. Genevieve 499 18,642 IntegrityGIS

Which counties face each other

The Census adjacency file pairs counties that share a boundary. Use it to find the county across the line from the one you know:

What changes when you cross the line

Researching a tract that crosses the line

  1. Find the parcel in both counties' viewers. Each side will show only its own piece, with its own parcel number.
  2. Pull the recorded deed from each county's register or recorder, since each county records only the land inside its own boundary.
  3. Expect two tax bills, one from each county, and check each state's rules for homestead or farm exemptions.
  4. For a sale, a fence or a building permit, hire a licensed surveyor familiar with the line; tax-map lines are drawings, not surveys.

A quick way to check which side a spot is on

Open the Platbookmapper Land Map, search the nearest county, and tap the spot. The land report shows which county it falls in, along with flood zone, elevation, soil and wetlands, and links to that county's parcel map.

Related guides

More: Illinois counties · Missouri counties

Sources