Getting back to the topic, I think a four-lane connection from Huntsville to I-75 at either Botkins or especially Beaverdam would pull a lot of traffic heading from Columbus and points southeast to Fort Wayne and Chicago as it avoids both the toll roads and the heavily-trafficked I-65/ I-70 corridor. It might also push Indiana add more limited access sections to US 30 from Fort Wayne to Valpo. This would more than justify the current four lanes from Huntsville to Columbus. Make that connection at Mount Cory and you have a legit alternative for the Toledo-Columbus corridor.
Just for fun, I ran the mileage between Huntsville, Ohio, where I used to exit from US 33 to Ohio 117 to get to Lima and then US 30:
1. US 33 > Ohio 117 > I-75 > Bluelick Road > Ohio 65 > Ohio 115 > US 30 > Fort Wayne City Hall (the way I used to go):
106 miles/1:542. US 33 > Ohio 117 > Phillips Road, etc. > US 30 @ Beaverdam > Fort Wayne City Hall:
98.9 miles/1:483. US 33 > Ohio 117 > Thayer Road > US 30 > Fort Wayne City Hall:
95.3 miles/1:424. US 33 > Ohio 117 > Ohio 235 @ Ada > US 30 > Fort Wayne City Hall: 104 miles/1:515. US 33 > I-75 @ Wapak > Bluelick Road > Ohio 65 > Ohio 115 > US 30 > Fort Wayne City Hall:
108 miles/1:55 6. US 33 > I-75 @ Wapak > US 30 @ Beaverdam > Fort Wayne City Hall:
117 miles/2 hours7. US 33 > Fort Wayne City Hall:
92.4 miles/1:47 hours#7 doesn't work because you have 60 miles of road to four-lane to the Indiana border.
#6 is the easiest solution because you only have to four-lane about 20 miles of road from Indian Lake to I-75, whereas most of the other options involve four-laning roughly 30 miles. But I still think you lose too many miles with this route--It's a whopping 22 miles more than #3. I think too many people are going to use the two-lane roads to avoid the extra 22 miles.
#4 I think is the answer because it also solves the Toledo-Columbus problem, four laning it all the way to I-75. It's only 10 miles more going to Columbus City Hall this way than using US 23 to Delaware, with no stops or traffic lights. The caveat is whether or not this 10 miles is a big deal to truckers or not.
I hate tearing up more farmland though.