I love winter trail running! The woods and mountains are transformed. New views open up through the bare trees. I get so much less sweaty in the lower temperatures. And the snowmobile trails offer routes that I am unable to run any other time of year.
Here in Maine, both local clubs and state-level leadership maintain thousands of miles of trails that cross both private and public land. The Interconnected Trail System (ITS) map gives you a sense of the scope of these networks. The ITS is an incredible source of tourism revenue for the state, especially in our most remote areas, which makes them comparable to busy highways. For your safely, I do not recommend that you run the the majority of this network.
Fortunately, smaller local snowmobile clubs maintain quieter networks of trails that are perfect to run on. These clubs provide maps which you can get from them directly or sometimes purchase at a local convenience store--look for the one where all the snowmobiles get gas. While you're out there, although it's not so busy as the ITS, make sure you take the same safety precautions that you would in any other kind of traffic. Expect trails to be busy on weekends and consider running elsewhere during busier days and times. Additionally, these trails may be narrow, so move over and let snowmobiles pass you instead of expecting them to yield to runners. Remember, you're in their house.
So why run on snowmobile trails when there are so many other trail running opportunities?
You're short on time. It's great to take a day-long adventure in the mountains, but what if you want to get in a shorter run before work. Hopping on the local snowmobile trails can give you a chance to get outside without mounting a full expedition. Bonus--few riders are out in the early morning, so you may just have the trails to yourself.
You're looking for comfortable trail footing. Running snowmobile trails give you the ease and pleasure of running on groomed snow without being the jerk who ruined the nordic trails. Leaving footprints on dedicated ski trails creates safety hazards for skiers, but snowmobiles don't have the same concerns. If you're new to trail running or rehabbing an injury, the snowmobile trails offer a way to get onto a smoother, stable trail surface while you build confidence and strength.
You'd like to run something otherwise inaccessible. The snowmobile trail that crosses the road by my parents' house brings me across a gorgeous marsh that I could never run unless it were frozen. Similarly, other trails travel through areas too wet to maintain as ATV or hiking trails in other seasons. And because snowmobiles need a snowpack, some landowners will allow snowmobile traffic (but not ATV access) because those machines do not damage or erode the ground beneath. This all adds up to trail access that is seasonal, so explore it while you can!
You're bad at navigating. Snowmobile trails are well mapped and well marked. Just follow the packed track through the snow and read the signs at intersections. If you have a bad sense of direction, these trails may be less confusing than singletrack.
You want to introduce a roadie to winter trail running. The packed trail offers clean footing, and while you may sometimes want screw shoes, you'll rarely need more aggressive traction devices. I have a running partner who only enjoys our trail outings in winter because he has more confidence on snowmobile trails than rocks and roots. It's nice to have a running strategy that's comfortable to both of us.
I'm lucky that I live in an area where an active snowmobile trail network offers miles of variety and adventure. It's perfect for a quick run or a long, slow adventure in the woods. If you're wanting to add something new to your winter routes, get on your shoes and head out onto your local network!