David Orkin uncovers a treasure trove of American memorabilia in big sky country

It was the sight of the martian outside the entrance that made me turn around, drive back and pull up outside The Miracle of America Museum (MoAM) just beyond Polson. Officially billed "Western Montana's Largest Museum", MoAM has been dubbed "the Smithsonian of the West". Yet this is no slick, well-funded enterprise: it's intrinsically small-town America.

A non-profit organisation, MoAM was founded by Gil and Joanne Mangels in 1985. It looks deceptively compact from Highway 93, but the building that faces the road is just the tip of the iceberg. When you enter you're thrown into what seems like a giant junk shop. Indian artefacts soon give way to kitchen equipment, followed by an 1898 sheep- powered treadmill and two dozen motorcycles. Move on to an extensive military display, which comprises more than 20 vehicles and memorabilia from the Spanish-American to the Gulf wars. See shredded White House-Iran contra documents, then turn the corner and you're confronted by a reconstructed 1950s soda fountain opposite a huge stuffed bison.

If it all gets a bit much, pop a 25 cent coin in the Orchestrion (a notice describes it as a "player-piano with other instruments built in") and grab your partner for a twirl.

Out in the yard you'll find Pioneer Village. You can walk through its 1890s general store stocked with period merchandise, look into a 1912 one-room school, and see a saddle and harness repair shop. You can also tour a two-storey barn housing one of the West's largest displays of barbed wire.

MoAM, you can't help feeling, is what displays of Americana should be all about: a collection of eccentric odds and ends. But despite the initial junk-yard impression, there is an overall theme.

Joanne Mangel says: "I would like people to walk out with an appreciation of America and the ingenuity of our forefathers."

The Miracle of America Museum (001 406 883 6804, www.cyberport.net/museum) at 58176 Highway 93, Polson, Montana, is open 8am-5pm Mon-Sat, 1.30-5pm Sunday (8am-8pm daily during the summer); adults $4 (£2.10)