Includes several maps. October, 2009, but not much change.
As you probably already know, there is no single “Big Sky Cutoff” (aka “Butte Super Cutoff”) as everyone inevitably takes a different variation, but I think the general route described in http://www.wildernesstravels.co.uk/cdt/bigsky.htm is a good place to start. I planned a variation of this for my wife and I’s CDT hike last year (2020) and I would recommend it if you want a Big Sky Cutoff with minimal logistics.
The benefits of this route are that you do not need to send a single box ahead, as all resupplies are done at real grocery stores in towns. Also, you can do this hike with only 2-3 campsite reservations in Yellowstone NP, yet you get to spend around a week’s worth of time in the park. It’s a nice compromise of a lot of time in the park without a lot of permits. Without further ado, I’ll give an overview with mileage of my own Big Sky Cutoff, presented in SOBO order because that’s what the OP asked for:
— Mileage / Resupply —
Butte, MT (via ~15 mile hitch from northernmost I-15 crossing on the CDT)
< 38.6 miles >
Whitehall, MT (on route, Jefferson’s Fresh Food resupply)
< 63.2 miles >
Ennis, MT (via ~7 mile hitch from Hwy-287 crossing at McAllister)
< 41.0 miles >
Big Sky, MT (on route, Roxy’s Market resupply… or take bus into Bozeman)
< 61.0 miles > (this includes 6.2 mi of road walking from Big Sky to Porcupine Creek TH and 6.0 mi of road walking from Mammoth Springs in Yellowstone to Gardiner)
Gardner, MT (on route, Gardiner Market resupply)
< 80.0 miles >
Cody, WY (via ~45 mile hitch from Eagle Creek CG on Hwy-14)
< 79.2 miles >
Dubois, WY (via ~26 mile hitch from Hwy-26 crossing on the old CDT)
— Maps —
Printable maps for most of this route can be downloaded at http://www.wildernesstravels.co.uk/cdt/bigsky.htm
High quality waterproof maps (and digital versions) of almost the entire route can be purchased from Beartooth Publishing. Specifically, you will want the following maps:
Tobacco Root Mountains, Bozeman / Big Sky / West Yellowstone, Yellowstone North, Yellowstone South
You could just buy the single Yellowstone National Park map for the Yellowstone stretch, but that version doesn’t have the specific backcountry campsites marked, so it is useless for trying to plan out campsite reservations while knowing mileage in between the sites. For that reason I’d suggest buying both the North and the South maps for Yellowstone, as linked above. You can try and plan out your campsite reservations using the official Yellowstone Trails & Campsites map, but without mileages in between the sites, it’s not very useful. I found just buying the Beartooth maps to be worth it, plus Beartooth Publishing is local company in Montana and they answered all of my email questions really kindly and were super informative and helpful, so I think it’s worth supporting this local business.
— Yellowstone NP Backcountry Camping Permits —
For more info on getting your backcountry permits for Yellowstone, check our the Camp in the Backcountry page on the YNP website.
When we went through Yellowstone (northbound, in our case), we only needed to get 2 nights worth of backcountry permits, because we did some very careful planning to camp right outside of the YNP border for multiple nights. It can be done.
Importantly, when you call ahead to reserve permits, it can be done no earlier than 3 days prior to the start of your trip, so you kind of need to call in when you are quite close to entering the park. With this in mind, I would recommend the following:
For SOBO hikers, you will want call in to get permits once you are in Big Sky, MT. It you can’t get permits there, it’s still possible to squeeze by and camp just outside the YNP boundary near Shelf Lake, then hike into Mammoth Hot Springs (where there is a campground) in one 29 mile day. You can walk 6 miles (or hitch) from Mammoth Hot Springs to Gardiner to resupply at the grocery store there. From Mammoth Hot Springs or from Gardiner, you could also call in to get your permits.
For NOBO hikers, you will want to call in to get your permits once you are in Cody, WY. Yes, you can hike through the park for multiple days before that without having to actually camp in it overnight. I would suggest the following schedule when entering the park from the south: camp at Bridger Lake, just south of the YNP boundary, hike 20 miles from Bridger Lake to just past Eagle Pass (where you get out of the park again) and camp around there, then hike another 15 miles from Eagle Pass to the Eagle Creek Campground at Hwy-14 (where you can hitch into Cody).
— Navigation —
Lastly, the OP asked about navigation… I found navigation relatively simple on the cutoff. The trails along the way are mostly very good and oftentimes marked, so a compass, a physical map, and a brain is mostly sufficient for navigation. If you get the digital versions of the Beartooth maps on the Avenza apps, then you can geolocate on the maps themselves. I would actually suggest the electronic maps for this reason. I actually purchased both for redundancy, but only really used the digital maps on trail. The physical maps were helpful to layout on the floor and plan the whole route though, and I liked being able to write directly on them too with notes.
Good luck!
https://www.reddit.com/r/CDT/s/A0PI7Ykhm9