Parts of the trail and some tunnel access are closed in winter. Memorial weekend is the official opening date each year. You must have a light and a ticket to enter either end of the trail. (It seems to be a free-for-all if you park anywhere other than the two trailheads).
The Hiawatha Bike and Hike Trail is public property. It is on U. S. National Forest land administered by the St. Joe Ranger District of the Idaho Panhandle National Forest. Like a ski mountain, it is operated by Lookout Pass Ski Area under a special use permit. There are "ski patrol" on the trail to help with breakdowns or injuries.
The official "Route of the Hiawatha Trail" is 15.1 miles, running from the East Portal, MT to Pearson, ID. (There is a lot of good running out each end as well). There are 9 of 10 train tunnels and 7 of 8 trestles on this trail that are still accessible. (One tunnel is unstable and closed. One trestle burned and is gone).
The longest tunnel is the St. Paul Pass Tunnel (Taft Tunnel or East Portal) at 1.66 miles. It is all downhill when starting at the East Portal. The trail itself used to be part of the railroad grade, so the way is well-maintained, and you won't come across too many obstacles. The Route of the Hiawatha is one of only 15 trails to be named a "Hall of Fame" trail by the Rail-to-Trail Conservancy.
You can get your trail passes and bus tickets at the trailheads (bring cash) or get them at Lookout Pass Ski Area just off I-90 at the state line. They also rent bikes at the ski lodge. Phone: 208-744-1234. There's also a shuttle bus service for an additional fee from Pearson, ID to the East Portal, MT.
From the bottom of the trail, there are a series of Forest Service roads which are pleasant and generally unchallenging if you're looking to explore more of the area.