(FORTUNE Small Business) – Every entrepreneur dreams that his brilliant idea will change the world. Throughout this issue, you've read stories of people who are accomplishing that goal today. But let's step back for a moment and take a longer view. Below, we look at some innovations that have shaped the country over the past two centuries. To make our list, these American innovators had to have come up with ideas that set their industries, from agriculture to fashion, on a different course. Each must have left a legacy that is still apparent today. And while some had great foresight and luck, others met with success only after enduring constant rejection and dozens of failed experiments. But they do share one trait: Each of their examples shows how entrepreneurs can change the country.

1837 JOHN DEERE

INNOVATION The self-cleaning steel plow

HOW IT CHANGED THE WORLD It sounds a bit technical: Deere designed the blades of his plow to clear themselves of heavy, moist soil as they moved. But that seemingly esoteric development revolutionized farming for pioneers traveling west in the mid-1800s. The soil on the frontier was much richer than back East, and before Deere's invention, farmers had to stop to clean the blades almost every two feet. And Deere was the first to make farming equipment a competitive industry: He hired farmers as subcontractors to sell plows to neighbors. By relieving himself of sales duties, he had time to improve his plows further.

LEGACY It's not too much to say that Deere is partly responsible for the westward spread of American civilization. What's more, Deere's manufacturing strategy--mass-producing plows before taking customer orders--put his machines into farmers' fields quickly, meaning that agricultural development moved even more rapidly. Hollywood has a different story about how the West was won, but this one is a bit more accurate.

1844 CHARLES GOODYEAR

INNOVATION Vulcanized rubber, used in Goodyear tires and hundreds of other consumer products

HOW IT CHANGED THE WORLD Before Goodyear, dozens of companies tried and failed to make rubber that wouldn't melt or freeze. Goodyear spent a decade experimenting and developing his breakthrough. The result: a flexible, weatherproof product now used in many industries. (Goodyear was also an early victim of intellectual-property theft: One of his imitators beat him to the European patent for vulcanized rubber.)

LEGACY Goodyear made rubber practical to use. That opened the door for diverse products such as Keds (the first sneakers), condoms (why do you think they're called "rubbers"? Early ones were made of the material), and tires. And then there's that blimp; where would the Super Bowl be without it? But if Goodyear had had his way, his legacy would be much farther-reaching. He envisioned some uses for rubber that never quite caught on. Turned out there just wasn't a market for rubber clothing or musical instruments.

1872 AARON MONTGOMERY WARD

INNOVATION Mail-order catalog for Montgomery Ward & Co.

HOW IT CHANGED THE WORLD You could call Montgomery Ward the first "virtual" department store. Ward designed his business to operate without a storefront--a radical move for a retailer at the time. (He didn't open a retail store until 1926.) The first edition of the Montgomery Ward catalog was actually a one-page list of 163 items, mostly farming equipment. Over the next 15 years, Ward's mail-order catalog grew to 280 pages and included thousands of items, accompanied by a money-back guarantee. With the help of his catalog, Ward made shopping cheaper and less time-consuming for farmers who couldn't take time away from their fields to travel several hours to stores.

LEGACY Sears' catalog may be better known today, but Ward's came out first. Ward was the one who proved that you could sell a department store's worth of goods through the mail, a lesson that Sears soon learned and followed. Ward's catalog also could be called the progenitor of Amazon.com, Dell Computer, and countless other e-tailers. Although the company finally went out of business in 2000--we told you it was the progenitor of e-tailers--its legacy is still with us. Today we can thank (or blame) Ward for those J. Crew and Pottery Barn catalogs clogging our mailboxes.

1873 LEVI STRAUSS

INNOVATION Levi's jeans

HOW IT CHANGED THE WORLD Strauss originally created denim pants for miners during the California gold rush--the cloth could take more of a beating than other kinds of material. But after Strauss and his business partner, tailor Jacob Davis, added rivets to make the pants more durable, jeans became fashion essentials.

LEGACY When Levi Strauss & Co.'s patent on riveted clothing expired in 1891, companies rushed to make their own versions of jeans. Hundreds of labels, from Calvin Klein to Diesel, have reinvented the pants to keep pace with clothing trends, but the denim and rivets remain. What's more, Levi's is still the bestselling clothing brand on the planet.

1876 ADOLPHUS BUSCH

INNOVATION Budweiser beer

HOW IT CHANGED THE WORLD Before Busch, beer was brewed locally and served only to niche audiences. Busch set out to deliver an accessible brew that would appeal to the entire country. He also developed a national network of icehouses and proved to brewers that beer wasn't just a regional business--it could transcend local tastes and sell on a national scale.

LEGACY Busch set the precedent for national beer production in the U.S., and its brands--Budweiser, Bud Light, Michelob, and others--have made it the largest beermaker in the country. Today, even with competitors like Coors and Miller, Anheuser-Busch controls about half the domestic beer market.

1886 DAVID MCCONNELL

INNOVATION Avon cosmetics

HOW IT CHANGED THE WORLD At a time when women rarely held jobs outside their own homes, McConnell tapped housewives to build a workforce of door-to-door saleswomen. He realized that some customers might be more trusting of saleswomen from their own social circles than traveling salesmen. Soon after McConnell launched his new sales tactics, business began to boom.

LEGACY Sixty years before the swing shift brought women into factories, McConnell proved that a female sales force could be a valuable asset. It's a lesson that was learned well by companies like Tupperware and Mary Kay, which soon adopted the concept of women selling to their peers. Even today the concept of "viral marketing" draws heavily on McConnell's original concept.

1888 GEORGE EASTMAN

INNOVATION The Kodak camera

HOW IT CHANGED THE WORLD Before Eastman, photographers had to lug around unwieldy, television-sized cameras, heavy tripods, and chemicals to develop their photographs. By scaling down and simplifying the equipment needed to take a picture, Eastman and his handheld camera made photography accessible to everyone.

LEGACY Photography has become one of the most widespread hobbies in the country, thanks to Eastman's popularization of the camera. Today every consumer camera--from disposable to point-and-shoot to digital--owes a debt to Eastman...and so does every amateur darkroom jockey.

1905 MILTON HERSHEY

INNOVATION Hershey's milk chocolate

HOW IT CHANGED THE WORLD Hershey was the first entrepreneur to successfully mass-produce chocolate, which until that time had largely been hand-made and expensive. His chocolate bar--the first of its kind--made the delicacy affordable: The first Hershey's bars cost 5 cents.

LEGACY After the introduction of the Hershey's bar, the Curtiss Candy Co. of Chicago came out with competing products like Butterfinger and Baby Ruth, and Mars jumped in with Milky Way and Snickers. And Hershey continued to innovate, with products like Reese's Peanut Butter Cups, Hershey's Kisses, and Twizzlers.

1922 J.C. NICHOLS

INNOVATION Country Club Plaza, the first shopping mall

HOW IT CHANGED THE WORLD Nichols's plan for a shopping district with inward-facing stores and plenty of available parking meant that consumers no longer needed to trek downtown to do their shopping.

LEGACY Nichols contributed to the rise of the suburbs, as his model served as a prototype for the automobile-centered malls of the 1950s. His ideas--like unified architecture, free parking, and fountains--are still found in malls today.

1926 DAVID SARNOFF

INNOVATION The hundreds of linked broadcast stations that would become the National Broadcasting Co.

HOW IT CHANGED THE WORLD In the early 1900s radio had been used primarily in shipping. But Sarnoff convinced his company, RCA, that the device held promise as a household product that would allow people around the country to listen to music, sports, and news programs. Then he proved his notion by coordinating the broadcast of a wildly popular prizefight between Jack Dempsey and Georges Carpentier in 1921. Radio took off from there, and Sarnoff set up the first national radio network to support it. Later he helped introduce television to crowds at the 1939 World's Fair and set up a station at NBC (RCA's subsidiary) to develop the medium.

LEGACY Thanks to Sarnoff, we have a national television industry. Ironically, the spread of television leapfrogged Sarnoff's first great breakthrough, commercial radio. (So there's truth to that old song lyric about video killing the radio star--or at least usurping it.) Nevertheless, without Sarnoff the broadcasting industry would look very different today--or might not exist at all.

1959 RUTH HANDLER

INNOVATION The Barbie doll

HOW IT CHANGED THE WORLD Before Handler, most dolls were modeled after babies and children. Handler created Barbie with the idea that girls wanted to play out their dreams for the future. Her doll--a professional-looking (if disproportionate) woman--became the bestselling toy line in the history of the industry. And Barbie's success made Mattel into the largest toymaker worldwide.

LEGACY Barbie accounts for about a third of Mattel's $5 billion in annual sales. Her popularity has changed the face of toymaking, inspiring other lines of career-themed dolls, like Smartees and Get Real Girl.

1962 SAM WALTON

INNOVATION Wal-Mart

HOW IT CHANGED THE WORLD Just as the developers of the shopping mall reaped profits from suburban consumers, Walton discovered a thriving retail market in rural America, particularly the small towns previously ignored by big business. Walton recognized that out in the hinterland consumers would travel farther for one-stop shopping; he could draw people not just from one small town but from the entire county. And his low-cost, customer-friendly philosophy helped popularize the chain. The resulting stores may not be as glamorous as Saks Fifth Avenue, but they've made Walton a legend, and Wal-Mart one of the most successful retail companies in history.

LEGACY Walton's business formula made Wal-Mart Stores the largest American retailer and helped the company develop brands like Wal-Mart Supercenters and Sam's Clubs, surpassing competitors like Kmart and Target. Though not the first to enter the wholesale club industry, Sam's Club is now a close No. 2 in the market, behind Costco, and like Wal-Mart has thrived in rural areas.