Delivering and picking up there is an adventure. As it is with any diesel yard and hump yard. Gotta have your head on a swivel. I've picked up there a couple of times and delivered there 4 or 5 times.
BNSF's Argentine Yard in Kansas City is the second largest, and is BNSF's biggest yard. The Argentine Yard in KC has 60 classification (sorting) tracks while the North Platte Bailey Yard has 114 classification tracks. So, yeah, there's big, and then there's big.
UP's Englewood Yard in Houston is really big, especially when you count in the adjacent intermodal Settegast Yard.
The Proviso Yard in Chicago is right up there, as is that massive yard in Barstow, whatever it's called.
And the CSX Rice Yard in Waycross, GA is easily in the Top 5, maybe at #3. It's one of my favorite places to pickup and deliver, although I haven't been there in a couple of years.