Multistate 4 corner US Counties

[America Needs a 13-6 Progressive SCOTUS]

In the United States, at the state level; there is only a single 4-corner area; New Mexico, Arizona, Colorado, and Utah.

Similarly, at the county level; there are tons of 4-corner areas; with especially large amounts in Michigan, Iowa, Texas, Kansas, and Nebraska. These are often simple. The state decided to create somewhere and sometime a neat square grid area of Counties. For the purposes of this thread, I will count cases where the counties have unequal angles (as in, not all 90 degrees), and by extension, also cases where there are more than just 4 Counties involved.

There are many subtle issues that make multistate 4 corner Counties much rarer. There is no opportunity for a single government organization to create a huge array of gridded Counties that form multistate 4 corner Counties. Even if multiple states both use grids, there is no guarantee that they will perfectly align, and in general, they usually do not align. Frequently, it has to be the result of the same specific natural feature or notable coordinate being used as the delineation of County borders by multiple neighboring states. Even then, that can be insufficient, if the state border slightly follows that feature in the process, as that skews the boundaries off point. For that reason, multistate 4 corner US Counties are very rare.

The most obvious example of a multistate 4 corner US County set is that inherited from the 4 corner states; San Juan in New Mexico, Apache in Arizona, Montezuma in Colorado, and San Juan in Utah (weird how 2 of these Counties share a name yet these are Counties on opposite non-connected sections of the corner).

Beyond that, it can often get complicated, sometimes even to the point where different sources will give a different answer. For example, loading West Virginia in Daves Redistricting app makes it appear that the Grant/Preston/Tucker trio in the state does not form a multistate 4 corner US County set with Garrett County in Maryland, as Grant and Preston Counties seem to slightly touch eachother, leaving a small gap in between Tucker and Garrett Counties; yet wikipedia lists all the Counties on eachothers listings for all the neighboring Counties to said County on their geography sections.

However, there are some cases where it definitely appears that a multistate 4 corner US County set exists beyond that. The states of Maryland and Pennsylvania appear to have both used the Susquehanna River as the dividing line between 2 of their Counties as the river crosses the Mason-Dixon line. Similarly, the states of North and South Dakota appear to have both used the Missouri River as the dividing line between 2 of their Counties.

[Kevinstat]

Beyond that, it can often get complicated, sometimes even to the point where different sources will give a different answer. For example, loading West Virginia in Daves Redistricting app makes it appear that the Grant/Preston/Tucker trio in the state does not form a multistate 4 corner US County set with Garrett County in Maryland, as Grant and Preston Counties seem to slightly touch eachother, leaving a small gap in between Tucker and Garrett Counties; yet wikipedia lists all the Counties on eachothers listings for all the neighboring Counties to said County on their geography sections.

Dave's Redistricting App (according to you, and I'm sure you're correct, I just haven't checked that out) is correct and Wikipedia was incorrect (I've just fixed the "Adjacent Counties" section in the Garrett County, MD and Tucker County, WV articles and put in a request to change the template for Tucker County, WV - the template for Garrett County, MD was correct, at least in its not showing Tucker County, WV as a bordering county).  See this PDF census block map from the U.S. Census Bureau web site.

[jimrtex]

There are many subtle issues that make multistate 4 corner Counties much rarer. There is no opportunity for a single government organization to create a huge array of gridded Counties that form multistate 4 corner Counties. Even if multiple states both use grids, there is no guarantee that they will perfectly align, and in general, they usually do not align. Frequently, it has to be the result of the same specific natural feature or notable coordinate being used as the delineation of County borders by multiple neighboring states. Even then, that can be insufficient, if the state border slightly follows that feature in the process, as that skews the boundaries off point. For that reason, multistate 4 corner US Counties are very rare.

The Public Land Survey System (PLSS) does not form a complete grid because it is impossible to fit squares to a sphere. If the east-west boundaries between townships are north-south, then the northern edge of the township is shorter than the southern edge. If you stacked townships, then they would be successively narrower.

The most obvious example of a multistate 4 corner US County set is that inherited from the 4 corner states; San Juan in New Mexico, Apache in Arizona, Montezuma in Colorado, and San Juan in Utah (weird how 2 of these Counties share a name yet these are Counties on opposite non-connected sections of the corner).

San Juan, Colorado is not adjacent to any of the other states. St. Johns is the county seat of Apache, Arizona.

Beyond that, it can often get complicated, sometimes even to the point where different sources will give a different answer. For example, loading West Virginia in Daves Redistricting app makes it appear that the Grant/Preston/Tucker trio in the state does not form a multistate 4 corner US County set with Garrett County in Maryland, as Grant and Preston Counties seem to slightly touch each other, leaving a small gap in between Tucker and Garrett Counties; yet wikipedia lists all the Counties on each others listings for all the neighboring Counties to said County on their geography sections.

The boundary line between Maryland and Virginia is the southern bank of the Potomac to its source. If the Potomac continued westward, then so would Garrett County.

Tucker, WV and Garrett, MD are clearly not contiguous. Neither Muon2 or myself are likely to consider Preston, WV and Grant, WV connected for redistricting purposes.

However, there are some cases where it definitely appears that a multistate 4 corner US County set exists beyond that. The states of Maryland and Pennsylvania appear to have both used the Susquehanna River as the dividing line between 2 of their Counties as the river crosses the Mason-Dixon line. Similarly, the states of North and South Dakota appear to have both used the Missouri River as the dividing line between 2 of their Counties.

The York-Lancaster line is on the west bank, while the Harford-Cecil line is mid-river. Therefore there is a boundary between Lancaster, PA and Harford, MD for the western half of the river.

The SD-ND case is odder. Emmons, ND and Corson, SD are adjacent. The boundary is in Lake Oahe. Presumably the boundary between Sioux-Emmons and Corson-Campbell followed the course of the Missouri prior to the building of the dam.

The boundary between Sioux, ND and Emmons, ND follows the course of the river, and this appears to be true throughout North Dakota. But the boundary between Corson, SD and Campbell, SD appears to be the midline of the lake. But once you have passed the Campell, SD- Walworth, SD boundary, the east-west boundary reverts to the course of the river. That is, the Corson, SD-Walworth, SD boundary is along the river course.

What is more odd, is that the Missouri River forms the eastern boundary of the Standing Rock Reservation, and it appears that there is a notch in the reservation boundary at the state line. At this point, the river course is in the western part of the lake, so that Emmons, ND east of the river and Corson, SD west of the lake midline are adjacent.

So was the boundary between Corson, SD and Campbell, SD along with the reservation boundary formally re-adjudicated to follow the mid-line of the lake.

[jimrtex]

Beyond that, it can often get complicated, sometimes even to the point where different sources will give a different answer. For example, loading West Virginia in Daves Redistricting app makes it appear that the Grant/Preston/Tucker trio in the state does not form a multistate 4 corner US County set with Garrett County in Maryland, as Grant and Preston Counties seem to slightly touch eachother, leaving a small gap in between Tucker and Garrett Counties; yet wikipedia lists all the Counties on eachothers listings for all the neighboring Counties to said County on their geography sections.

Dave's Redistricting App (according to you, and I'm sure you're correct, I just haven't checked that out) is correct and Wikipedia was incorrect (I've just fixed the "Adjacent Counties" section in the Garrett County, MD and Tucker County, WV articles and put in a request to change the template for Tucker County, WV - the template for Garrett County, MD was correct, at least in its not showing Tucker County, WV as a bordering county).  See this PDF census block map from the U.S. Census Bureau web site.

This would in general be the most reliable single source, but it should be noted that census geography might not follow actual boundaries. OTOH, since census geography is based on county boundaries (i.e. census tracts, block groups, and census blocks properly nest) it might be presumed that county boundaries are observed.

County Adjacency File

[jimrtex]

However, there are some cases where it definitely appears that a multistate 4 corner US County set exists beyond that. The states of Maryland and Pennsylvania appear to have both used the Susquehanna River as the dividing line between 2 of their Counties as the river crosses the Mason-Dixon line. Similarly, the states of North and South Dakota appear to have both used the Missouri River as the dividing line between 2 of their Counties.

The SD-ND case is odder. Emmons, ND and Corson, SD are adjacent. The boundary is in Lake Oahe. Presumably the boundary between Sioux-Emmons and Corson-Campbell followed the course of the Missouri prior to the building of the dam.

The boundary between Sioux, ND and Emmons, ND follows the course of the river, and this appears to be true throughout North Dakota. But the boundary between Corson, SD and Campbell, SD appears to be the midline of the lake. But once you have passed the Campell, SD- Walworth, SD boundary, the east-west boundary reverts to the course of the river. That is, the Corson, SD-Walworth, SD boundary is along the river course.

What is more odd, is that the Missouri River forms the eastern boundary of the Standing Rock Reservation, and it appears that there is a notch in the reservation boundary at the state line. At this point, the river course is in the western part of the lake, so that Emmons, ND east of the river and Corson, SD west of the lake midline are adjacent.

So was the boundary between Corson, SD and Campbell, SD along with the reservation boundary formally re-adjudicated to follow the mid-line of the lake.

It appears that the boundary in South Dakota has been re-adjudicated.

1966 Topo maps show the county boundaries along the river course as "undefined".

Oahe Dam was built from 1948-1958 and was filled for electricity production by 1962.

Current Topo maps show the boundary following the middle of the reservoir south of the state line. Perhaps it has something to do with fishing rights for the reservation?

Thus Sioux, Emmons, Corson, and Campbell ceased to co-adjacent in the latter part of the 20th Century. If the boundary north of the state line were moved to the center of the reservoir they would be co-adjacent once again.

[Kevinstat]

However, there are some cases where it definitely appears that a multistate 4 corner US County set exists beyond that. The states of Maryland and Pennsylvania appear to have both used the Susquehanna River as the dividing line between 2 of their Counties as the river crosses the Mason-Dixon line. Similarly, the states of North and South Dakota appear to have both used the Missouri River as the dividing line between 2 of their Counties.

The SD-ND case is odder. Emmons, ND and Corson, SD are adjacent. The boundary is in Lake Oahe. Presumably the boundary between Sioux-Emmons and Corson-Campbell followed the course of the Missouri prior to the building of the dam.

The boundary between Sioux, ND and Emmons, ND follows the course of the river, and this appears to be true throughout North Dakota. But the boundary between Corson, SD and Campbell, SD appears to be the midline of the lake. But once you have passed the Campell, SD- Walworth, SD boundary, the east-west boundary reverts to the course of the river. That is, the Corson, SD-Walworth, SD boundary is along the river course.

What is more odd, is that the Missouri River forms the eastern boundary of the Standing Rock Reservation, and it appears that there is a notch in the reservation boundary at the state line. At this point, the river course is in the western part of the lake, so that Emmons, ND east of the river and Corson, SD west of the lake midline are adjacent.

So was the boundary between Corson, SD and Campbell, SD along with the reservation boundary formally re-adjudicated to follow the mid-line of the lake.

It appears that the boundary in South Dakota has been re-adjudicated.

1966 Topo maps show the county boundaries along the river course as "undefined".

Oahe Dam was built from 1948-1958 and was filled for electricity production by 1962.

Current Topo maps show the boundary following the middle of the reservoir south of the state line. Perhaps it has something to do with fishing rights for the reservation?

Thus Sioux, Emmons, Corson, and Campbell ceased to co-adjacent in the latter part of the 20th Century. If the boundary north of the state line were moved to the center of the reservoir they would be co-adjacent once again.

Interestingly, the (counter-clockwise from northeast, like quadrants in Cartesian coordinates) Sioux, ND-Adams, ND-Perkins, SD-Corson, SD quartet (PDF) on the other side of the Standing Rock Reservation comes closer to being a 4-corner boundary than the Emmons, ND-Sioux, ND-Corson, SD-Campbell, SD quartet (PDF, same scale) does.  In both cases the 1-dimensional (as opposed to 0-dimensional, i.e. point) boundary includes Corson County, SD, so it borders three North Dakota counties (Adams, Sioux and Emmons) while Sioux County, ND borders only one South Dakota county (Corson).  The reservation boundary follows the county boundaries (with a jog in the reservation boundary along the state line) in both cases.

[jimrtex]

Interestingly, the (counter-clockwise from northeast, like quadrants in Cartesian coordinates) Sioux, ND-Adams, ND-Perkins, SD-Corson, SD quartet (PDF) on the other side of the Standing Rock Reservation comes closer to being a 4-corner boundary than the Emmons, ND-Sioux, ND-Corson, SD-Campbell, SD quartet (PDF, same scale) does.  In both cases the 1-dimensional (as opposed to 0-dimensional, i.e. point) boundary includes Corson County, SD, so it borders three North Dakota counties (Adams, Sioux and Emmons) while Sioux County, ND borders only one South Dakota county (Corson).  The reservation boundary follows the county boundaries (with a jog in the reservation boundary along the state line) in both cases.

It would be cool if the railroad (now BNSF) crossed the Adams, ND-Corson, SD border.
In Texas, it used to be possible to sue a railroad in any county where they had rail lines. Plaintiffs would forum shop to get a jury more favorable to claims against the railroad. Railroads would pull little-used branch lines to avoid liability.