Most geographically extreme/central interchanges in a state

[Hot Rod Hootenanny]

Ohio

Central: I-71 and OH 13 (8.5 miles from Memorial Park in Centerburg)

Incorrect on all accounts.
According to ODOT, the geographical center of Ohio is an 1/2 north of Olive Green Rd in Porter Twp, Delaware County. (between Moody Rd & the Delaware/Knox County line)
Exit 169 for I-71 (@ Oh 13) would be 32 miles from this point (and 31 1/2 miles from Centerburg)

The correct answer for "most centered" interchange in Ohio would be I-71 @ Oh 61 (exit 141) at 7 1/3 miles from ODOT's centroid (and 11 1/2 miles from yours).

[SkyPesos]

Ohio

Central: I-71 and OH 13 (8.5 miles from Memorial Park in Centerburg)

Incorrect on all accounts.
According to ODOT, the geographical center of Ohio is an 1/2 north of Olive Green Rd in Porter Twp, Delaware County. (between Moody Rd & the Delaware/Knox County line)
Exit 169 for I-71 (@ Oh 13) would be 32 miles from this point (and 31 1/2 miles from Centerburg)

The correct answer for "most centered" interchange in Ohio would be I-71 @ Oh 61 (exit 141) at 7 1/3 miles from ODOT's centroid (and 11 1/2 miles from yours).

I meant I-71 and OH 61 as 8 miles west of the geographic center. No idea where I got OH 13 from.

[ran4sh]

It is somewhat easier to identify Georgia's extreme and central system (freeway-to-freeway) interchanges:

Central: I-75 exit 156, I-475
South: I-516 exit 2, Veterans Parkway
East: Technically I-16 exit 166, US 17 north. One could argue that that shouldn't count because I-16 is not much more than a set of ramps east of there, in which case the answer would be the I-16 & I-516 interchange.
North and west: I-24 exit 167, I-59

[Scott5114]

The most geographically central interchange in Oklahoma is pretty easy to figure out, because, according to Google Maps, the center of Oklahoma happens to lie in the middle of Kelley Avenue in north Oklahoma City.


Note that I measured from the cross street here. If you instead prefer to measure from the center of all ramps, then the US-77/Kilpatrick interchange is a couple hundred feet closer.

The geographic center of Oklahoma has 4.5 stars on Google Maps, by the way.

[sparker]

Since CA has, well, a truly weird physical configuration, establishing extremes might be a bit of a challenge.  But here we go anyway:

EAST:  Virtual tie between I-8 at Winterhaven, I-10 at the east end of the Blythe business loop, and I-40 at old US 66 just west of the Colorado River (the "cutoff" to south US 95).
SOUTH: (helped by the fact that the Mexican border with Baja is slanted a bit WSW-ENE:  the split of I-5 and I-805 directly north of the Tijuana border crossing.
WEST:  the Fernbridge (CA 211) and/or Loleta interchanges on US 101 in Humboldt County between Fortuna and Eureka.
NORTH:  This one's easy; the Hilts interchange (#796) on I-5 just south of the OR state line.
CENTRAL:  The closest freeway interchange to the geographical center of the state (just calculating without extensive platting) may just be the CA 99/CA 152 interchange near Chowchilla. 

[GaryV]

Michigan:
Northern: I-75 and Easterday Avenue just south of the Canadian border in Sault Ste. Marie
Southern: US 23/US 223 at Stearns Road near Lambertville
Eastern: I-94/I-69 and the M-25 connector just west of the Blue Water bridge toll plaza in Port Huron
Western: I-94 and M-239 in New Baltimore
Central: US 10/US 127 and Bus. US 10/Bus. US 127  at Clare if going off the freeway network in the state. Based on the whole state, it would be I-75 and BL I-75/M-32 at Gaylord, the closest interchange to the geographic center near Elmira, based on pure latitude and longitude.

This site is one of several I've seen
https://www.netstate.com/states/geography/mi_geography.htm#:~:text=The%20geographic%20center%20of%20Michigan,miles%20north%2Dnorthwest%20of%20Cadillac.&text=Michigan%20is%20a%20unique%20state,peninsulas%20into%20the%20Great%20Lakes.
that says that the geographic center of MI is in Wexford Co. So the center-most intersection would be one of the ones on US 131.

[Bruce]

Washington:

North - I-5 and SR 548 (exit 276) in Blaine
South - SR 14 and SE Union Street (exit 14) in Camas - the Columbia River dips far enough south to edge out Vancouver
East -  I-90 and Appleway (exit 299) near Liberty Lake
West - US 12 and Devonshire Road/Pioneer Avenue near Montesano
Central - SR 28 and SR 285 in East Wenatchee (Geographic center is apparently south of Wenatchee in the highlands)

Washington (freeways only):

North - I-5 and SR 543 in Blaine
South - I-205 and SR 14 in Vancouver
East - I-90 and SR 290 in Spokane
West - US 101 and SR 8 near Olympia
Central - US 2/97 and SR 285 near Wenatchee

[bulldog1979]

Michigan:
Northern: I-75 and Easterday Avenue just south of the Canadian border in Sault Ste. Marie
Southern: US 23/US 223 at Stearns Road near Lambertville
Eastern: I-94/I-69 and the M-25 connector just west of the Blue Water bridge toll plaza in Port Huron
Western: I-94 and M-239 in New Baltimore
Central: US 10/US 127 and Bus. US 10/Bus. US 127  at Clare if going off the freeway network in the state. Based on the whole state, it would be I-75 and BL I-75/M-32 at Gaylord, the closest interchange to the geographic center near Elmira, based on pure latitude and longitude.

This site is one of several I've seen
https://www.netstate.com/states/geography/mi_geography.htm#:~:text=The%20geographic%20center%20of%20Michigan,miles%20north%2Dnorthwest%20of%20Cadillac.&text=Michigan%20is%20a%20unique%20state,peninsulas%20into%20the%20Great%20Lakes.
that says that the geographic center of MI is in Wexford Co. So the center-most intersection would be one of the ones on US 131.

Yet, if you actually input the latitude and longitude given for the center point, it's by Elmira.

[andrepoiy]

Ontario:

East: Highway 401 and CR-23 (https://www.google.ca/maps/@45.2024796,-74.4015383,14z)
West and probably North: Highway 17 and Hodder Avenue (https://www.google.ca/maps/@48.4827485,-89.1821731,16z)
South: Highway 401 and Highway 3 (https://www.google.ca/maps/@42.234372,-82.9872945,16z)

[DandyDan]

For Iowa
North: I-35 and County 105 west of Northwood (Exit 214)
South: I-35 and US 69 south of Lamoni at the Missouri border
West: I-29 and IA 12 in Sioux City
East: I believe US 30 and County Z36 near Low Moor is further east than I-80 and US 67 by LeClaire.

[epzik8]

Maryland:

North: I-83 at Freeland Road in Parkton, though I-68/70/US 522 in Hancock comes close and part of I-81's Pennsylvania exit 1 is in Maryland
South: South end of the Sailsbury Bypass (US 13)
East: US 113/MD 90 in Ocean Pines
West: I-68 at MD 42 in Friendsville
Center: MD 3 at Belair Drive (with ramps to and from US 50) in Bowie

[froggie]

Maryland:
East: US 113/MD 90 in Ocean Pines

You forgot MD 90/MD 589...

[jaehak]

Kansas

West - I 70 at K267 in Kanorado.
East - 435 at State Line Road (but half of the interchange is in Missouri)
North - US 36 at US 73 in Hiawatha
South - I 35 at US 160
Central - the geographic center of Kansas is really in the boonies, but surprisingly quite near a random interchange between K4 and K156

Freeway to freeway

East - 70 at 670
North - 70 at 435
South - 35 at 135
West AND Central - 70 at 135

[bulldog1979]

I just looked up the extreme points of Michigan on Wikipedia, which doesn't agree with that website. (Checking the points on a map checks out.) Michigan ranges from 46°33'58"N at the point in the border with Canada to 42°35'28"N at the IN—MI—OH tripoint in the north—south direction and 88°22'11"W at the Montreal River near Ironwood to 84°48'22"W at a corner in the Canadian border in Lake Huron in the east—west direction. Averaging each pair gives a midpoint of 45°4'43"N 86°36'6"W, which is in the middle of Lake Michigan about 20 miles WNW of Glen Haven in the Sleeping Bear Dunes, or about 5.7 miles from the maritime Wisconsin state line. It actually looks like the closest interchange to that point is going to be the northern Bus. US 41 and US 41 interchange at Peshtigo, Wisconsin! (It's 61 miles from the point in the lake, vs. 66 miles to the US 131 and M-42 interchange at Manton.)

[hotdogPi]

Averaging each pair gives a midpoint of...

Michigan isn't a rectangle.

[Flint1979]

The most central intersection in the Lower Peninsula is probably M-46 and US-127.

I'll go with M-55 and M-115 for the entire state.

[sprjus4]

North Carolina

Southern - US-17 / NC-130 in Shallote
Northern - US-29 / US-58 just south of Danville, VA
Western - US-74 / US-19 (Exit 64) in Bryson City
Eastern - US-17 Bypass / NC-344 (Exit 258) in Elizabeth City
Central - I-73/I-74 / NC-1002 (Exit 52) in Star

[JayhawkCO]

Colorado:

West: I-70 Exit 2 - Rabbit Valley
East: I-70 Exit 438 - BL  I-70 and US 24
South: I-25 Exit 2 - Wootton
North: US 138 at US 385 on the northeast side of Julesburg

Most central: The geographical center of Colorado is 39°N, 105°32'48"W which is just south of US 24 between Hartsel and Lake George. This location is 47 miles southeast of I-70 Exit 195 - CO 91 Copper Mountain, 40 miles west northwest of I-25 Exit 141 - US 24 West (which, as a crossroads interchange, could be the emotionally central interchange of the state, sorry I-70), and 37 miles west southwest of  I-25 Exit 161 - CO 105 Monument.

However, the closest interchange to the center at 30.4 miles north of the center is along US 285 northeast of Bailey at Park County Road 43 and Park County Road 72 - Deer Creek.

And then just to add to this, since I drove by the SW one Saturday that made me think of this thread.
Northwest: I-70 & CR215 in Parachute
Southwest: US160 @ Mesa Verde National Park
Northeast: I-76 & US385 in Julesburg
Southeast: US50 & US287 in Wiley

Chris