Essvee, I spent my first 20 years in Joplin and hang out there for about three months a year. You want local color? I got yer local color right here: Fred & Red’s, a chili place at about 17th & Main. It moved to its current spot in the 1940s. Except for the prices, little has changed. Former residents make a pilgrimage to the place and reminisce about going there when they were kids (right before the cafe closes for August, it ships chili bricks all over the country). Fred & Red’s is no-nonsense and working-class like the town itself. There are no tables, only a U-shaped counter. Smoking is allowed anywhere, though few people light up. The waitresses sass their regular customers. Kind of like "Cheers" with a cholesterol problem.
It doesn’t have a website. Heck, it doesn’t even have a phone.
Charlie’s Chicken, a chain based in NE Oklahoma, serves up a tender and spicy rotisserie chicken on 32nd Street about a half-mile east of Range Line. You’re on the edge of the south and are starting to get into okra country. That’s my preferred side dish at Charlie’s.
I agree with SFreader that the Red Onion is a fine upscale option as is its sister restaurant, Bella Pepper’s, at about 24th & Range Line.
Skip the town’s Steak & Shake. I love the chain, but the local franchise has a reputation for poor service. If Fred & Red’s doesn’t give you enough "time travel," go to one of the two Steak & Shakes in Springfield, about 70 miles to the east. I believe at least one of the restaurants is listed on the National Register of Historic Places.
Roadfood reviewed Clanton’s Cafe in Vinita, Oklahoma (http://www.clantonscafe.com/) on Route 66. It’s a 50-mile trip down I-44. The same distance south takes you to AQ Chicken in Springdale (http://www.aqchicken.com/), which, I believe, also recieved a Roadfood mention (and deserved it).
Writing this post has made me hungry. Wish I were in Joplin.