Ashton-Flagg Ranch Lake Road

Total Miles33.6
Technical Rating
3Easy
Best TimeSummer, Fall
Trail TypeFull-Width Road
Accessible By
Open Trail Map

Trail Overview

This backcountry drive connects Flagg Ranch near Yellowstone's south entrance to the farmlands surrounding Ashton, Idaho. The road travels between the roadless Winegar Hole Wilderness to the north and the Jededia Smith Wilderness to the south, both of which are home to the grizzly bear. While much of the route burrows through dense forest, there are numerous lakes and bogs along the way. The main trunk road passes by Grassy Lake Reservoir and Indian Lake. Several other short side roads can be driven to reach Lake of the Woods, Moose Lake, Loon Lake, and Bergman Reservoir. Keep watch for trumpeter swans in these riperian areas. The east side of the road has over a dozen dispersed campsites along the Snake River. Fuel, a convenience store, and additional lodging options are available at Flagg Ranch.

Photos of Ashton-Flagg Ranch Lake Road

Difficulty

Most of this route follows easy, wide gravel roads, but sections on the east side are narrow and can become rough, muddy, and rutted. Only high-clearance vehicles should attempt this drive. Watch for slower horse-drawn wagons on the Idaho side. Winter travel is not recommended.

History

Utilizing a historic native trail, the road was built in 1911 by the Bureau of Reclamation to transport construction materials from Idaho to Wyoming. Some maps still label this route as the Reclamation Road while others use the more modern names of Grassy Lake Road or Ashton-Flagg Ranch Road.

Technical Rating

3

Status Reports

Add Status Report
Gavin Czajkowski
Jul 26, 2026
2004 Lexus Gx470
Open
Dusty
normal gravel road coming in from the west, some braking bumps and potholes but in general you could do the whole thing in a prius. there is a bit of a rut about 2 miles into wyoming that might be difficult for a sedan. watch for oncoming traffic on the blind corners
Nathaniel Rogers
Jun 09, 2026
2019 Toyota Tacoma
Open
Rough/Deteriorated
Trail was open from the Teton side (Headwaters at Flagg Campground). Only went to the dam, road has some potholes and bumpy sections but nothing impassable.
Sarah Tunget
May 25, 2026
2025 Subaru Outback
Temporarily Closed
Seasonal ClosurePosted SignClosed Gate
Tried to enter from the Teton Side. Gate closed with no information on when it will open.
Nick Trull
May 21, 2026
2021 Toyota 4Runner
Temporarily Closed
Ashton side closed, I called the number and they said gate was in fact closed on both ends for snow. Wouldn’t open until late June
Phil Murphy
Oct 02, 2025
Open
Normal
Gorgeous fall colors, and well worth the time to take this beautiful trail!
ZAK Kindle
Jul 31, 2025
2010 Toyota Sequoia
Open
NormalDusty
Great back country road full of history into the Yellowstone National park. Many lakes and camp sites along this road with bear boxes. Lots of wild life and information signs along the road.
Saylor Schott
Jul 19, 2025
Open
Dusty
Jennifer Heath
Jun 19, 2025
Open
NormalWashboard
Easy trail, mostly gravel and rough in patches at higher elevation. Lower portion has lots of flowers.
Colin A
Jun 14, 2025
2023 Toyota Tacoma
Temporarily Closed
Seasonal ClosurePosted Sign
Austin brown
Jun 08, 2025
Temporarily Closed
Posted Sign
Jared Smith
Jun 01, 2025
2019 RAM 2500
Temporarily Closed
Seasonal Closure
Connor Hemmers
May 30, 2025
Temporarily Closed
Colin Arner
Nov 03, 2024
Temporarily Closed
Seasonal Closure
Charlie Stump
Jul 29, 2024
2017 Honda CRF1000L
Open
Mario Rego
Jul 02, 2024
Open
NormalDusty

Ashton-Flagg Ranch Lake Road Trail can be accessed by the following ride types:

  • Single Track
  • 50 Inch
  • 60 Inch
  • High Clearance
  • Full Width

Ashton-Flagg Ranch Lake Road Map

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