1956 Harley-Davidson 165
When you think of lightweight off-road motorcycles, you probably don't think of Harley-Davidson. But there was a time in the late '50s when, thanks to the ingenuity of rider Leroy Winters, Harley was on the cutting edge of the lightweight off-road movement.

1962 Manx Norton 500
These days, four-stroke motocross machines are phasing out two-strokes, which have dominated the sport since the 1960s. But there was a time, long ago, when two-strokes did the same to four-strokes. And the last of the old guard they replaced were thumpers like this one.

1963 Husqvarna Racer
This is the bike that started a revolution. Without this machine--and the vision of the man who imported more like it--American motocross might never have gotten off the ground.

1963 Monark 500
When you think of Sweden and off-road bikes, what name comes to mind? Husqvarna, right? Yeah, it was brand H that put Scandinavia on the map by the time motocross made it big in this country in the late '60s. But well before then, there was another Swedish company making its name in the sport--a now-obscure marque called Monark.

1969 Jawa CZ360
The CZ was a top-shelf machine for its day, featuring an integrated gearbox, a dry clutch, a twin-plug ignition system and a rear brake integrated into the sprocket-side of the magnesium hub casting.

1971 Titanium Husqvarna
When Swedish MX star Lars Larsson lined up on this bike for the 1971 Indian Dunes motocross race in Southern California, his competition thought he was on a regular Husqvarna. But Larsson knew better. He was aboard one of the rarest machines in the history of American motocross: a 400cc Husqvarna with a frame made of titanium.

1973 Honda RC250 Works Bike
By the 1970s, two-strokes reigned as the kings of motocross racing. And Honda wanted the crown. Trouble was, the company, which had built its U.S. reputation on four-stroke streetbikes, didn't have anything to compete against the light and powerful oil-burners of its competitors. So Honda built a two-stroke--the now-legendary Elsinore motocross bike.

1976 Husqvarna CR360
Swedish manufacturer Husqvarna is famous for helping ignite the motocross revolution in America. But, amazingly, the brand has earned only a single AMA national motocross title. And this was the bike that won it.

1976 Rokon MX2
The Japanese invasion of American motocross may have been in full force by the mid-1970s, but there was still room for serious innovation. Case in point: The unique approach to motorcycle design by Vermont-based Rokon, which produced this unusual MXer with a fully automatic transmission.

1978 Harley-Davidson MX 250
Good swing, no follow-through. That about sums it up for Harley-Davidson's brief foray into the world of motocross. The project started in the late 1970s, when Harley, under the control of leisure-products conglomerate AMF, decided to test the market with its first-ever motocrosser.

1982 Suzuki RN Racer
Talk about a warhorse. That's what this Suzuki motocrosser was for the legendary "Bad" Brad Lackey back in 1982, when he used it to survive the rabid, pro-European fans and claim the first, and only, 500cc World Motocross Championship won by an American racer.

1985 KX250 MX Racer
In the early 1980s, exotic, one-off factory bikes ruled the motocross world. And few of them were more successful than Jeff Ward's 1985 KX250 machines. In fact, in one frenzied eight-day period, Jeff Ward rode works KX250s to clinch not one, but two national championships.

Donny Schmit's 1990 Suzuki
Many of the bikes in the Motocross America exhibit tell the story of technological progress and innovation. This bike tells the story of one very determined racer.

The King's 1995 CR250
When it comes to AMA Supercross, there's one true king: Jeremy McGrath. Although he would wrap up his championship run on Yamahas, it was on Hondas like this 1995 machine that the king established his empire.

Chad Reed's 2004 YZ250
Today, four-strokes dominate the premier class of the AMA Amp'd Mobile Supercross Series, but in 2004, faster-revving two-strokes still dominated on the series' tight, technical indoor tracks. The fastest of them all that year? Chad Reed's Yamaha YZ250.