What is the most heavily used interchange for each interstate in your state?

[noelbotevera]

I do not know for PA north of I-78, so I will only do the southern half of the state. I have also not been on I-276, and I-76 west of I-376. Here goes.

I-76: Tricky, but I'd say exit 236 (US 15). Traffic levels drop east of Harrisburg, and do not pick up until you are at Valley Forge.
I-78: Exit 51/53, as US 22 is I-78's emergency route east of Allentown. Also, I-78 gets clogged on the PA 309 concurrency, so a ton of traffic will clog US 22.
I-81: Hard for me, but I'd say Exit 65A-B or Exit 67A-B. US 11/15 is a great scenic way to get up to New York, while US 22/322 is a great way to get to Hershey or New York City (via 22 EB).
I-83: Exit 44A/Exit 45. Paxton St. will carry US 322 to Hershey, and PA 230 is the way around Harrisburg, and you could easily make it to the capitol via Paxton.
I-283: Exit 1, PA 283, since that is the fastest way to Lancaster.
I-376: This is completely different territory for me, but I would say Exit 72A-B-C. I am likely to be wrong, but that's the way to PA 28, I-579, and other major streets in Pittsburgh (traffic levels increase west of the Squirrel Hill Tunnel, AFAIK).
I-579: I don't know.

[iBallasticwolf2]

I-579: I don't know.

I don't know much about Pittsburgh but I would guess that most I-579 traffic is destined for the Liberty Bridge or Blvd of. the Allies (In turn trying to get to I-376). In that case the ending interchange would probably be the most used.

[jeffandnicole]

Here's some guesses for Washington. I don't know where to find the actual stats. I excluded freeway-to-freeway junctions. Below, freeway-to-freeway refers to junctions that are entirely grade-separated and have no signals (so are either partial stacks, trumpets, etc) but do not necessarily connect to another freeway. I did not want to include junctions that were literally between two freeways, as those are easily picks.

I-5: Mercer Street (Exit 167), Downtown Seattle. Junction originally built for Bay Freeway (so it's freeway-to-freeway) but has become the main interchange for South Lake Union and points west.
I-405: Junction for either NE 4th or NE 8th near Downtown Bellevue (Exit 13B).
I-205: Mill Plain Blvd (Exit 28). I'm not including any of I-205 in Oregon.
I-90: Either the Bellevue Way or WA-18 junctions (Exit 9 and 25, respectively). Can't decide which. The former is freeway-to-freeway, but the latter is a diamond, so the 18 junction feels busier to me.
I-82: Most likely US-395 (Exit 113). Like others before, it's freeway-to-freeway, but US-395 is a very important connector between Canada and points south.
I-182: Most likely WA-240 (Exit 4). Also freeway-to-freeway. The 240 is a fairly important NW/SE connector road.

Washington has a lot of freeways without Interstate designation; this list would be very long if I included them all, but the original post just asks for Interstates, so that's what I've supplied.

I would say the OP was very clear he's only interested in including interstate highway interchanges, and excluding Interstate-Interstate interchanges.  No need to make the question harder than it is.

[jakeroot]

<clipped>

I would say the OP was very clear he's only interested in including interstate highway interchanges, and excluding Interstate-Interstate interchanges.  No need to make the question harder than it is.

Nahhh, I was just making it more interesting.

[cl94]

I do not know for PA north of I-78, so I will only do the southern half of the state. I have also not been on I-276, and I-76 west of I-376. Here goes.

I-76: Tricky, but I'd say exit 236 (US 15). Traffic levels drop east of Harrisburg, and do not pick up until you are at Valley Forge.
I-78: Exit 51/53, as US 22 is I-78's emergency route east of Allentown. Also, I-78 gets clogged on the PA 309 concurrency, so a ton of traffic will clog US 22.
I-81: Hard for me, but I'd say Exit 65A-B or Exit 67A-B. US 11/15 is a great scenic way to get up to New York, while US 22/322 is a great way to get to Hershey or New York City (via 22 EB).
I-83: Exit 44A/Exit 45. Paxton St. will carry US 322 to Hershey, and PA 230 is the way around Harrisburg, and you could easily make it to the capitol via Paxton.
I-283: Exit 1, PA 283, since that is the fastest way to Lancaster.
I-376: This is completely different territory for me, but I would say Exit 72A-B-C. I am likely to be wrong, but that's the way to PA 28, I-579, and other major streets in Pittsburgh (traffic levels increase west of the Squirrel Hill Tunnel, AFAIK).
I-579: I don't know.

I'm going to help complete this:

I-79: Either I-70 Exit 19 (US 19) or Exit 78
I-279: Exit 1C (US 19/PA 65)
I-579: "Downtown Exits" (especially if you include the HOV lane)
I-80: Either Exit 210 (US 15) or Exit 302 (PA 33)
I-180: US 15/US 220/Future I-99 at the NT
I-380: Exit 3 (PA 940) or Exit 8 (PA 423/PA 611/Army Depot)
I-84: Exit 53 (US 6)
I-86: Exit 3 (PA 89). Only exit in the state. If the section in South Waverly is officially I-86 as Google Maps appears to indicate, Exit 60 (US 220) probably beats it.
I-90: Exit 24 (US 19). Nothing else comes remotely close.

[peterj920]

Wisconsin

I-39/I-90: Interchange with the Beltline (US 12/18) Exit 142
I-41: Interchange with US 10/Wis 441 Exit 134
I-43: Interchange with Wis 172 Exit 180
I-94: Interchange with Wis 175 (Stadium Interchange) Exit 308
I-794: Lake Interchange Exit 1F
I-894: Wis 59 Exit 1C (Zoo Interchange Alternate Route)

[mgk920]

Wisconsin

I-39/I-90: Interchange with the Beltline (US 12/18) Exit 142
I-41: Interchange with US 10/Wis 441 Exit 134
I-43: Interchange with Wis 172 Exit 180
I-94: Interchange with Wis 175 (Stadium Interchange) Exit 308
I-794: Lake Interchange Exit 1F
I-894: Wis 59 Exit 1C (Zoo Interchange Alternate Route)

I-41 might be close with WI 172 (Ashwaubenon interchange), too.
I-43 might also be WI 100 (Brown Deer Rd).
I-535 - 2nd St/3rd St (only interchange on highway in Wisconsin).
Where does WI 241 (27th St) rank on I-894?

Mike

[swbrotha100]

I'll take a shot at a few in Arizona.

I-8: AZ 85
I-10: AZ 51/Loop 202
I-17: Loop 101
I-19: Valencia Rd
I-40: US 93 in Kingman

[cl94]

Connecticut:

I-95: I-91/CT 34 in New Haven
I-91: Toss up between I-84 in Hartford and I-95/CT 34 in New Haven.
I-84: I-91 interchange in Hartford.
I-395: I-95 interchange in Waterford.
I-384: I-84/I-291 interchange in East Hartford.
I-291: I-91/CT 218 interchange in Windsor.
I-691: I-95/CT 15/CT 66 interchange in Meriden.

OP specified that Interstate-Interstate junctions are exempt

[JakeFromNewEngland]

Connecticut:

I-95: I-91/CT 34 in New Haven
I-91: Toss up between I-84 in Hartford and I-95/CT 34 in New Haven.
I-84: I-91 interchange in Hartford.
I-395: I-95 interchange in Waterford.
I-384: I-84/I-291 interchange in East Hartford.
I-291: I-91/CT 218 interchange in Windsor.
I-691: I-95/CT 15/CT 66 interchange in Meriden.

OP specified that Interstate-Interstate junctions are exempt

Oops. Didn't read that. 

[JakeFromNewEngland]

Redo of Connecticut:

I-95: CT 8/CT 25 interchange in Bridgeport.
I-91: CT 15/US 5 interchange in Hartford.
I-84: Both of the US 7 interchanges in Danbury.
I-384: US 44/US 6 interchange at the terminus.
I-291: US 5 interchange.
I-691: US 5 interchange in Meriden.
I-395: CT 2 interchange in Norwich.

[empirestate]

Connecticut:

I-95: I-91/CT 34 in New Haven
I-91: Toss up between I-84 in Hartford and I-95/CT 34 in New Haven.
I-84: I-91 interchange in Hartford.
I-395: I-95 interchange in Waterford.
I-384: I-84/I-291 interchange in East Hartford.
I-291: I-91/CT 218 interchange in Windsor.
I-691: I-95/CT 15/CT 66 interchange in Meriden.

OP specified that Interstate-Interstate junctions are exempt

Oops. Didn't read that. 

Don't feel bad; pretty much nobody ever does these days.

(And not just here in this forum, but anywhere on the Internet, and in real life as well. I actually feel as if something has fundamentally changed in our society, where effect no longer follows directly from cause, nor response from stimulus. But maybe it's always been this way, and I just notice it more as I get older and more crotchety.)

[corco]

Montana, best guess:

I-90- US 93/Reserve St, Missoula
I-15- since unsigned I-315 can't count, probably US 12/US 287 in Helena
I-94- tossup between the MT-59 exit in Miles City and the MT-16 exit in Glendive

[Rothman]

I'll take a shot at a few in Arizona.

I-8: AZ 85

Really?  I would have gone with US 95.

[TravelingBethelite]

Here's my shot at Connecticut:
I-84: Going with the consensus, CT 8 in Waterbury
I-91-If many exits can be combined, US 5, If not, then Route 15/Berlin Turnpike
I-95-CT 8/25 in Bridgeport, followed by CT 9 in Old Saybrook
I-384-CT 83 towards Glastonbury
I-291-US 5 to CT 30 in South Windsor
I-395-US 6 in Killingly, followed by US 44 in Putnam
I-691-US 5 to Berlin Turnpike

most------->least used

[ekt8750]

I do not know for PA north of I-78, so I will only do the southern half of the state. I have also not been on I-276, and I-76 west of I-376. Here goes.

I-76: Tricky, but I'd say exit 236 (US 15). Traffic levels drop east of Harrisburg, and do not pick up until you are at Valley Forge.
I-78: Exit 51/53, as US 22 is I-78's emergency route east of Allentown. Also, I-78 gets clogged on the PA 309 concurrency, so a ton of traffic will clog US 22.
I-81: Hard for me, but I'd say Exit 65A-B or Exit 67A-B. US 11/15 is a great scenic way to get up to New York, while US 22/322 is a great way to get to Hershey or New York City (via 22 EB).
I-83: Exit 44A/Exit 45. Paxton St. will carry US 322 to Hershey, and PA 230 is the way around Harrisburg, and you could easily make it to the capitol via Paxton.
I-283: Exit 1, PA 283, since that is the fastest way to Lancaster.
I-376: This is completely different territory for me, but I would say Exit 72A-B-C. I am likely to be wrong, but that's the way to PA 28, I-579, and other major streets in Pittsburgh (traffic levels increase west of the Squirrel Hill Tunnel, AFAIK).
I-579: I don't know.

I'm going to help complete this:

I-79: Either I-70 Exit 19 (US 19) or Exit 78
I-279: Exit 1C (US 19/PA 65)
I-579: "Downtown Exits" (especially if you include the HOV lane)
I-80: Either Exit 210 (US 15) or Exit 302 (PA 33)
I-180: US 15/US 220/Future I-99 at the NT
I-380: Exit 3 (PA 940) or Exit 8 (PA 423/PA 611/Army Depot)
I-84: Exit 53 (US 6)
I-86: Exit 3 (PA 89). Only exit in the state. If the section in South Waverly is officially I-86 as Google Maps appears to indicate, Exit 60 (US 220) probably beats it.
I-90: Exit 24 (US 19). Nothing else comes remotely close.

I-95: Probably a tie between the Airport interchange and the PA 611/Broad St. Sports Complex interchange.
I-276: Tie between the Horsham (PA 611) and Bensalem (US 1) interchanges
I-476 (Blue Route): Exit 5, US 1 Lima/Springfield
I-476 (NE Extension): Exit 56, US 22 Lehigh Valley

[iBallasticwolf2]

Kentucky
I-75: KY 18 or KY 922
I-71: KY 35 or if you count the I-75 concurrency KY 18.
I-64: Probably Exit 4 to US 60.
I-65: Not sure.
I-69: Probably the Pennyrille and Western Kentucky Parkway interchange.
I-24: Either Exit 7 or the Pennyrille Parkway.
I-275: Either Exit 82 or Exit 77.
I-471: Most likely Exit 3 to KY 1892.
I-264: A tie between US 60 exit 20 or US 60/US 31W exit 8.
I-265: Most likely exit 32 because of the Ford Motor Plant.