State Park / State Forest · Montana
Big Arm Unit (Flathead Lake SP)
Near Big Arm, Montana — $24–$45 a night and rigs to 50 ft by our record.
Quick answer
Can I bring an RV to Big Arm Unit?
What length RV fits Big Arm Unit? Our record: Big Arm Unit takes rigs up to 50 ft. 9 months ahead via MT State Parks portal. Book on the operator's own page.
- Open: Our record: May through September.
Camping at Big Arm Unit? Tell us the nights.
One email when a Montana owner lists a rig for those nights.
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On the ground
Largest Flathead Lake state-park unit. Wild Horse Island day-trip from the marina — wild horses + bighorn sheep. Sites on the bluff have the dawn lake view.
From our record
- Open
- May through September
- Booking
- 9 months ahead via MT State Parks portal
- On site
- Water + electric, Showers, Pets allowed, Fire rings
- Camping styles
- RV-friendly, Tent camping, Cabins
What a posted rig limit measures
- Pad length — the rig plus anything it tows
- Height — what the branches and the awning need
- Turning arc — the swing off the loop road
Keep planning Montana
More Montana campgrounds
Around Big Arm
The rest of the Montana trip
Big Arm Unit (Flathead Lake SP) questions
- What length RV fits Big Arm Unit?
- Our record: Big Arm Unit takes rigs up to 50 ft.
- When is Big Arm Unit open?
- Our record: May through September.
- How do I reserve a site at Big Arm Unit?
- 9 months ahead via MT State Parks portal. Book on the operator's own page.
Before you go
Montana rules for RV renters
Montana rules
Verified 2026-05-10
- Rental tax
- 0%
- Min driver age
- 18+ · 21+ Class A
- Gravel roads
- Allowed
- Generator quiet hours
- 22:00-08:00
- Alcohol in cabin
- No open container
- Dump station
- Permissive