Guides/Overland routes/Wyoming
Overland route64 midifficulty: moderate

Seminoe to Alcova Back Country Byway

RegionWyomingAgencyBureau of Land ManagementLast verified—
Seminoe to Alcova Back Country Byway — overland route near Sinclair, Wyoming, Wyoming
Photo by Bob Wick / BLM via Wikimedia Commons (public domain)
Trail vitals6 facts
Length
64mi
Technical difficulty
Moderate
Direction
Point to point
Vehicle
High-clearance vehicle. Most of the byway is graded gravel passable to passenger cars; the north section over the Seminoe Mountains has heavy washboard and steep grades better handled in 4WD.
Best months
May, Jun, Jul, Aug, Sep, Oct
Cell coverage
None on most of the byway
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The Seminoe to Alcova Back Country Byway is a 64-mile graded-gravel route through south-central Wyoming, running between Sinclair on Interstate 80 and Alcova on Wyoming Highway 220. The route crosses pronghorn-grazed prairie, climbs the rugged Seminoe Mountains, and follows the Miracle Mile of the North Platte River — a blue-ribbon trout fishery — before passing Pathfinder and Alcova reservoirs in the north.

Most passenger cars handle the byway in dry conditions May through November. The section north of Seminoe State Park over the Seminoe Mountains has steep washboarded gravel that benefits from high-clearance and 4WD. There are no services between Sinclair and Alcova, so a full fuel tank and a good spare are essential. The byway includes a small dune section that's part of the Killpecker Sand Dunes complex stretching west into Wyoming.

Hazards

Read before you go

  • Seminoe Mountains washboard. Heavy washboarding and steep grades. High-clearance recommended.
  • Wind. Strong sustained wind across the prairie. Trailers and high-profile vehicles take a beating.
  • No services. No fuel, water, or cell coverage on the byway.
  • Wildlife. Pronghorn cross the road frequently at dawn and dusk.
  • Snow. Closes the Seminoe Mountain section December through April.
  • Tire damage. Sharp gravel sections puncture sidewalls.

Location

64 mi · Overland route

Approx. location 42.150, -106.870

Trail facts

5 fields
AgencyBureau of Land Management
Nearest townSinclair, Wyoming
Websitewww.blm.gov/visit/seminoe-alcova-backcountry-byway
ClosedDec, Jan, Feb, Mar
Approx. location42.150, -106.870

Getting there

Directions

Southern access (Sinclair). From Interstate 80 Exit 219, exit at Sinclair. The byway begins at the junction of I-80 and Carbon County Road 351.

Northern access (Alcova). From Casper on Wyoming-220, drive 32 miles southwest to Alcova. The byway begins at the junction of Wyoming-220 and Natrona County Road 407 (Kortes Road).

Approximate midpoint coordinates (Seminoe Reservoir area): 42.150° N, -106.870° W.

Photos

2 photos

Photos · 2

Field notes

Getting Oriented

The byway runs through Carbon and Natrona counties in south-central Wyoming. Sinclair (population ~400) on I-80 anchors the southern access; Alcova (population ~80) on Wyoming-220 anchors the northern. Casper, the regional service hub, is 32 miles north of Alcova. Seminoe State Park surrounds Seminoe Reservoir at roughly the midpoint, with developed camping and a marina.

Trail Overview

From Sinclair, take Carbon County Road 351 north. The first miles cross sagebrush flats; the road climbs gradually into the Seminoe Mountains. The Miracle Mile of the North Platte sits in this stretch, with several BLM access points and trout fishing turnouts. North of the river, the byway becomes its toughest section — washboarded gravel climbing into the Seminoe Mountains with steep grades. Past the mountains, the byway descends through Seminoe State Park along the reservoir shoreline.

After the state park the byway crosses Pathfinder Reservoir's north end, then continues to Alcova at the junction with Wyoming-220. Driving the full byway without stops takes 2 to 3 hours. With fishing, photography, or sand-dune stops, plan a full day.

Points of Interest

  • Miracle Mile. A blue-ribbon trout section of the North Platte. BLM access turnouts.
  • Seminoe Reservoir. Marina, swimming, and developed camping at Seminoe State Park.
  • Seminoe Mountains. Granite range with the byway's roughest section.
  • Pathfinder Reservoir. Larger reservoir north of Seminoe.
  • Alcova Reservoir. A third reservoir near the northern end.
  • Killpecker Sand Dunes (eastern arm). A small sand dune complex along the byway.
  • Pronghorn herds. The byway crosses some of Wyoming's densest pronghorn winter range.

Where to Camp

Seminoe State Park has developed campgrounds with fees, water, and modern restrooms. Dispersed camping is allowed on most BLM portions of the byway with the standard 14-day stay limit. Pathfinder Reservoir has a developed campground on the federal-water side.

Tips for a Safe and Enjoyable Trip

  • Visit May through November. Snow closes the Seminoe Mountain section the rest of the year.
  • Top off fuel in Sinclair, Casper, or Rawlins. There are no services on the 64-mile byway.
  • Carry water and basic tools.
  • Cell service is absent. Carry an offline map.
  • Watch for pronghorn, mule deer, and bighorn sheep in the Seminoe Mountains.
  • The Seminoe Mountain section is where most flat tires happen. Carry a full-size spare.
  • Wind can be aggressive across the high prairie; plan accordingly.
  • Contact the BLM Rawlins Field Office at 307-328-4200 for current conditions.

Frequently asked

Common questions

How difficult is Seminoe to Alcova Back Country Byway?
Seminoe to Alcova Back Country Byway is rated moderate. The route runs 64 miles.
What kind of vehicle do you need for Seminoe to Alcova Back Country Byway?
High-clearance vehicle. Most of the byway is graded gravel passable to passenger cars; the north section over the Seminoe Mountains has heavy washboard and steep grades better handled in 4WD.
When is the best time to visit Seminoe to Alcova Back Country Byway?
The best months are May, Jun, Jul, Aug, Sep, Oct. Avoid Dec, Jan, Feb, Mar.
Is there cell service at Seminoe to Alcova Back Country Byway?
None on most of the byway