One Exit Control Cities

[hobsini2]

Technically, Tomah WI (which is a secondary control city) falls under this. I-94 has 1 exit at US 12/WI 21 (Exit 143) that directly accesses Tomah. I-94 has a 2nd exit (with I-90) but does not access Tomah without exiting again off I-90 at either US 12/WI 16 or WI 131.

What about the Industrial Ave interchange?
http://goo.gl/maps/h0QS

That must have been added recently. I do not recall a 2nd Tomah exit on I-94.  It's been about 3 years since I was up there.

[roadman65]

I-270 in OH has only one exit each for its control cities of Cincinnati, Dayton/Indianapolis, Cleveland, Wheeling, Grove City, Dublin, Westerville, and Obetz. 

I'm sure you wouldn't count the first 4, as they are actually I-70 and I-71's control cities, but I think the 4 local control cities (used at most service interchanges) mostly count.  Grove City appears on just one exit from I-270, though it's listed on two exits from I-71 and another exit on I-270 could be informally described as a Grove City exit.  Dublin has just one exit from I-270, and one or two from US 33. Westerville appears on signage for just one exit, though another exit also leads to part of Westerville. Obetz appears only on auxilliary signage for one I-270 exit, I think.

But maybe you'd prefer to exclude 3-digit Interstates altogether...

Sure they count Wheeling and Indianapolis are used (or once were) on I-71 at both junctions with I-270, and Cleveland and Cincinnati are used on I-70 at both beltway junctions.  Dayton too was added to some signs when I was there in 03.

[PHLBOS]

In NJ, I-195 only has one exit for Shore Points

Similar can be said for MA 3 and MA 25 only have one "exit" (ramps from rotaries, actually) for Cape Cod.  The ramps from I-195 East to MA 25 East and I-495 South becoming MA 25 East would be I-195 & I-495's one exit for Cape Cod as well.