It was listed on the National Register of Historic Places in 2006.
The sign for the "start" of Route 66 in Chicago is actually on Adams St. a block East of Michigan Ave which is not where the "official" geographic start of Route 66 is. This is also approximately a mile from where Lou Mitchell's is.
If you're an out of towner, I guess that's "close" to where Lou Mitchell's is I suppose.
Lou Mitchell's isn't really that close to Union Station, or at least the main entrances that commuters actually use on Adams St. or on Madison St. It's also not popular due to its "proximity" to Union Station.
It's popular because the food is great, it's reasonably priced for being in Chicago and it's one of the last old-school diners left in the city. I can name the others for you if you like, and we can start with Manny's Delicatessen. I've been there too, it's the very last old-school Jewish style cafeteria left in all of Chicago.
It's not close (by my definition of "close") to the start of Route 66 and it's not even on the route. People may indeed eat there first before hopping on Route 66, but it's not the "first stop on the Mother Road" because it's not actually on Route 66.
Where did you copy and paste that from, a Wiki somewhere? That's kinda what it looks like.
Ate there many times. Best feta omelets and Greek toast ever.