How many left exits or left entrances?

[Alps]

I-280 East to 6th Street - Newark, NJ
I-78 East to Clinton Street - Newark, NJ
I-78 East to NJ 24 - Summit, NJ (I believe this is one?)
Garden State Parkway North to NJ 50 - Seaville, NJ
At least one in the conglomeration of highways around Newark Liberty International Airport

Yes, you're correct.  Don't forget I-80 EB's left entrance from US 46 at Exit 47A and all the mess at the GW Bridge.

[Beeper1]

In eastern CT:

I-95 NB at exit 86 (CT 184) in Groton
I-95 SB at exit 87 (CT 349) in Groton
I-395 SB at exit 78 (CT 32) in Montville
I-395 NB at exit 98 (CT 12) in Thompson
and I guess I-95 NB exit 76 (I-395) is one now, but of course that used to be the mainline.
Both of the I-95 ones also have left entrances.

In Rhode Island I can only think of four:

I-95 NB at exit 11 (I-295) in Warwick
I-95 SB at exit 9 (RI 4) in Warwick
US 6 WB at RI 14 in Providence
RI 37 WB at exit 4A (I-95 SB) in Cranston

The only left entrances I can think of in RI are:
US 6 EB from RI 14
I-295 NB from RI 37 EB
RI 37 EB from I-95 SB

[bulldog1979]

The Grand Rapids metro area has a few.

In the interchange between I-196 and I-296/US 131 there are the following left exits that become left entrances:
NB US 131 to WB I-96
SB US 131 to EB I-96
EB I-196 to NB US 131
WB I-196 to SB US 131

There are left entrances at:
EB M-45/Lake Michigan Drive to EB I-196
WB M-45 to WB I-196
WB BS I-196 to WB I-196
the east side of Chicago Dr to WB I-196
M-37/Alpine Ave. to EB I-96
WB M-11 to WB I-96
SB BUS US 131 to SB US 131
WB M-6 to WB I-196

There are left exits at:
WB I-196 to M-11/28th St/Wilson Ave
WB I-96 to WB I-196
NB US 131 to I-96 (using I-296) with a a left entrance on WB I-96 from I-296
NB I-296 to M-37/Alpine Ave.
NB US 131 to Wealthy St. (with a left entrance to NB US 131)

[Truvelo]

I can think of thousands of left exits near me but only a handful of right exits

[codyg1985]

I honestly don't think Huntsville has any left exits at all (primarly because I-565 was built in the 80's and 90's after left exits had been discouraged). The closest ones I can think of to me would be I-20/59/65 interchange in Birmingham, as sglaughlin mentioned, or I-24/59 junction close to Chattanooga, which has left exits for I-24W->I-59S and I-59N->I-24W. Same interchange configuration for I-24/I-75, I-24/I-40 (both interchanges), and I-65S/I-40.

[hbelkins]

I'm having trouble thinking of any left exits on West Virginia's interstate system, as well, excepting freeway-to-freeway connections.

[mightyace]

I can think of thousands of left exits near me but only a handful of right exits

Well for those of you from the UK or other places that drive on the left, I think listing right exits would be appropriate.

[NE2]

I'm having trouble thinking of any left exits on West Virginia's interstate system, as well, excepting freeway-to-freeway connections.

There's a left entrance from 36th to I-77 north in Charleston. Other than that, when the WV Turnpike ended at a trumpet there were technically left exits and entrances from and to the main I-77 path.

[74/171FAN]

Around Richmond: (first three both)
I-295 NB to I-95 NB(Exit 43A)
I-95 SB to I-295 SB(Exit 84A)
I-95 SB to I-295 NB(Exit 46)
I-295 SB to I-95 SB (left entrance south of Petersburg, not really a left exit(or counted as an exit but the exit to I-95 NB is though) as the mainline basically merges onto it even though I-295 SB ends here)

Salem/Roanoke: (both, second due to the end of the road)
I-81 SB at I-581/US 220 SB(Exit 143)
I-581/US 220 NB to I-81 SB

[Coelacanth]

Mn/DOT has been actively trying to remove left exits as interchanges are reconstructed. Recently removed have been SB I-35W to EB MN-62 and NB I-35W to WB MN-62/NB MN-121.

Still remaining (off the top of my head)

WB MN-62 to WB US-212*
NB I-35W to "Downtown Exits" (fka MN-65)
SB I-35W to EB MN-36 and SB Cleveland Avenue
WB I-94 to 6th Street (downtown St. Paul)
NB MN-252 to WB MN-610

I am probably forgetting one or two others.

* For mainline MN-62 traffic, the movement to US-212 is more accurately described as a freeway split rather than a left exit. However, traffic entering 62 from US-169 or Gleason Road must cut across the 3-lane MN-62 and take a second-chance type left exit.

[kj3400]

Baltimore:
almost all of them are on the Beltway.. 

-@ I-95 exit 64 (though no more  )
I-695E to I-95 N
I-695W to I-95S
I-95N to I-695W
I-95S to I-695E

-I-695 exit 4
I-695 E to I-97S
I mean they just take a lane and a half to go nowhere but Annapolis...

-I-695 exit 31C
I-695E to MD 43E

-I-695 exit 36
I-695S to MD 702S

-MD 295S to I-195E

-I-83N to MD 25

-US 29 exit 22
US 29S to MD 100E

And that's just the ones I know of or see regularly.

[SSOWorld]

Wisconsin:

Eagle Point Rd - left entrance only NB to US 151 near Dubuque

Mitchell Blvd in Milwaukee - all except WB exit are left
Old FW-FW interchanges (Zoo, Stadium, Hale, Mitchell (soon to be rid of them, sort of.))
Van Buren from I-794 - all except EB Entry
Lincoln Mem Dr from/to I-794 EB
Badger Interchange in madison (FW-FW)
WIS 29 W to I-39 S in Wausau (part of FW-FW)
Weigh Station on I-39 near Coloma is in the median
Though technically not a freeway exit - US2 W to US 53 S is a left "exit" (it's actually a protected left turn lane)

IIRC - Several Kansas Turnpike Service Areas are in the median

Illinois - I-94/US 41 South split (SB Only) before the toll road terminus

[Tourian]

Birmingham, AL's I-20/59 - I-65 interchange has the following left-lane exits:  I-65 NB to I-20/59 WB/SB,  I-20/59 WB/SB to I-65 SB, I-20/59 EB/NB to I-65 NB , and I-65 SB to I-20/59 EB/NB are all left exits, with corresponding left entrances.

Those are all interstate interchanges. IS that what the OP is looking for? I imagine there are a lot of those and they aren't all that special. The one left hand exit I can think of in Birmingham is indeed on 20/59 like right in front of the Civic Center. 125A or B I think. You leave the interstate and it drops down to street level. Always causes a bottleneck in that area during rush hour because people just don't expect it.

[jdb1234]

Birmingham, AL's I-20/59 - I-65 interchange has the following left-lane exits:  I-65 NB to I-20/59 WB/SB,  I-20/59 WB/SB to I-65 SB, I-20/59 EB/NB to I-65 NB , and I-65 SB to I-20/59 EB/NB are all left exits, with corresponding left entrances.

Those are all interstate interchanges. IS that what the OP is looking for? I imagine there are a lot of those and they aren't all that special. The one left hand exit I can think of in Birmingham is indeed on 20/59 like right in front of the Civic Center. 125A or B I think. You leave the interstate and it drops down to street level. Always causes a bottleneck in that area during rush hour because people just don't expect it.

There are also two left hand entrances to I-20/59 at the same interchange.  I-59 South to I-459 south is a left exit and the ramp from I-459 North to I-59 South is a left entrance.

[rte66man]

Oklahoma City

-all are freeway to non-freeway interchanges

I44 Westbound
   Classen Blvd exit
   Northwest Expressway exit
I44 Eastbound
   Classen Blvd entrance
   
NOTE: the one mile stretch of I44 between Western and Northwest Expy has way too many on and off ramps. If you are westbound, there is a right exit, left entrance, left exit, right entrance, and left exit in less than one mile.  The road was designed and built in the late 70's when I thought they knew better......

[J N Winkler]

Well for those of you from the UK or other places that drive on the left, I think listing right exits would be appropriate.

I think right-hand exits off motorways in GB are an exclusively Scottish phenomenon.

[english si]

There's one on the Leeds Inner Ring Road, but it could be considered the A58(M) mainline (though there's diverge markings, not a lane drop). There's also 2 right merges and one right diverge on the top deck of the double deck section of the A167(M) in Newcastle - though both of them were planned to be freeway-freeway interchanges and IIRC there's lane gains/drops there. Both of these are piddling little motorways covering a mile or two around a city centre with no freeway connection to the rest of the network.

There's also the right hand entrance at M60 j25, though again, freeway-freeway interchange was planned there.

But other than that, I can only think of the two or three in Glasgow (M8 j15 and j17), though again, j15 was planned as a freeway-freeway interchange, and j17 was a freeway-expressway interchange. Both have lane drops.

Now it's been modified, does the A56/A682 have a right merge or diverge, rather than being left exit/entrance for the A56 to/from the north?

[TheStranger]

Northern California...

West Sacramento, I-80 at US 50 (result of I-80 being moved off the mainline of US 50 and onto what was I-880).  For a few years, I-880 was a left exit off of I-80 in Foothill Farms, in anticipation of the never-finished I-80 realignment (that would've had it continue as the left mainline, the lanes of which are now used as light rail right of way).

Sacramento, Route 99 and Business 80 (originally I-80) at US 50.

San Francisco...in addition to the ramp from I-280 SB to US 101 SB, the ramp from I-280 NB to US 101 NB also does this (this was once the US 101 mainline).  Marina Boulevard exits off the left from US 101 south in the Presidio.

On I-80 itself, the 7th Street and 5th Street ramps from the Skyway are both left exits.

US 101 southbound to I-80 east is a left exit, though at one point 80 did continue west of there.

I-580/I-880 exits from the left of I-80 westbound at the MacArthur Maze likewise, thanks to the 1984 extension, the exit for I-80 west from I-580 west is a left ramp (though this was once the US 50 mainline).  At the Benicia Bridge's north end, I-780 exits from the left of I-680, but this was originally the 680 mainline until 1976.

I-580 exits off of the left of I-5 in Vernalis; originally, 580 was to be the 5W western suffixed branch of the mainline interstate, though the numberings had changed by the time the route was built.

On I-580 west in Castro Valley, 238 comes off on the left while 580 west takes the right lanes to continue onto the MacArthur Freeway.

Due to the reconstruction of the Central Freeway, at Van Ness Avenue for the last two decades, US 101 continues on the right while the left hand lanes lead to surface streets.

[SteveG1988]

I think everyone has forgotten about this, the 295/76/NJ42 mess south of camden,  the exit for I-76 exits left on southbound 295, the left merge from 76 once you stay on 295, etc.

http://maps.google.com/maps?q=camden+NJ&oe=utf-8&client=firefox-a&ie=UTF8&hq=&hnear=Camden,+New+Jersey&gl=us&ei=JcvrTMKoD8Kblgf1veBo&oi=geocode_result&ved=0CCIQ8gEwAA&ll=39.871837,-75.09799&spn=0.019334,0.052314&t=h&z=15

and the left hand exit/start of NJ90

http://maps.google.com/maps?q=camden+NJ&oe=utf-8&client=firefox-a&ie=UTF8&hq=&hnear=Camden,+New+Jersey&gl=us&ei=JcvrTMKoD8Kblgf1veBo&oi=geocode_result&ved=0CCIQ8gEwAA&ll=39.975657,-75.011215&spn=0.009652,0.026157&t=h&z=16

[Bickendan]

I-405 North in Portland is practically an entire left exit in itself! From I-5 North to I-405 North is a left exit, not to mention the very first exit (SW Naito Pkwy) is a left exit. Continuing on I-405 North, the next left is US 30 West, which is then followed by the US 30 East exit (technically just a movement to I-5 South). Other examples of a left exit in the Portland metro area:
I-5 South -> I-405 North
I-5 South -> Mt. Hood Freeway (the ghost ramp still exists)
Outside of the metro area, I-84 at Multnomah Falls (both directions)

Two you missed: US 26 (Sunset Hwy) east to I-405 north and to SW Market St -- two left exits in the same interchange!
And I-84/US 30 west to I-205 north/south, as the signed routes exit the mainline.

[njroadhorse]

Few more
New Jersey:
I-80 East to I-280 East in Parsippany

Virginia:
US 17 South has a left entrance onto I-66 East in Faquier County
I-81 South to I-581 South in Roanoke
US 460 West to US 460 Business West in Christiansburg

[wandering drive]

Filling gaps...

I-94 EB to MN-280 NB
I-94 WB to I-35W SB
That goofy interchange between Snelling Ave and I-694 where NB and SB Snelling Ave have left exits to go WB and EB respectively and each merging onto the freeway from the left. 
WB MN-36/SB MN-95 to SB MN-95

NB US-151 to NB BUS US-151 in Beaver Dam, WI

[SteveG1988]

Heres one, the left hand parking lot on the atlantic city expressway in NJ. http://maps.google.com/maps?q=atlantic+city+NJ&oe=utf-8&client=firefox-a&ie=UTF8&hl=en&hq=&hnear=Atlantic+City,+Atlantic,+New+Jersey&ll=39.388547,-74.506917&spn=0.004867,0.013078&t=h&z=17

[golden eagle]

In the Jackson area, I-55 northbound to Woodrow Wilson Boulevard is the only freeway-to-non-interstate with a left exit. There's also a left exit from Woodrow Wilson to I-55 north. I-20 west used to have a left exit to State Street, but a major reconstruction project has taken that lane away. Other left-turn exits from the interstates:

I-55 northbound to I-20 westbound
I-20 westbound to I-55 southbound
I-20 eastbound to I-55 northbound (just past the Pearl River/Rankin County line)
I-20 eastbound to I-220 northbound
I-220 southbound to I-20 eastbound
I-220 northbound to I-55 northbound

Before the Stack interchange was built, there used to be a left exit to get from I-55 south to I-20 east.

[wriddle082]

Discounting freeway-to-freeway connections, I can't think of any on Kentucky's interstate system.

There is a left exit on I-264 westbound at Dixie Highway southbound (US 31W/60) (Google Maps calls it Exit 8B, but I think it's really 8A).  Yes, your "favorite" part of Kentucky!

As for Tennessee, there's the I-40 eastbound ramp to US 25W/70 south/east in Newport (Exit 432B), and other than freeway-to-freeway that's technically about it.  I'm not counting the northbound Plough Blvd. on-ramp to I-240 west because Plough is practically a freeway.  One could also argue that I-55 has left exits north and south in the cloverleaf interchange just east of the Memphis-Arkansas Bridge, but that's silly.