On this day in economic and business history ...

Two members of the Dow Jones Industrial Average (DJINDICES:^DJI) got started on their path to business leadership on April 21, and one former member reached one of the most impressive milestones of its industry. Each has a radically different business model, but all three recognized the importance of marketing to their continued growth from an early stage. Let's take a look at these events, and at one other important milestone that occurred on a far earlier April 21.

Big Pharma's foundations
(NYSE:PFE) traces its origins to 1849, when two German cousins founded Charles Pfizer & Company in Brooklyn to sell a flavored antiparasitic medicine. However, it was not until April 21, 1900, that Pfizer became a corporation rather than a partnership by filing papers in the state of New Jersey. By then it was already a leader in the chemical industry, but it would be nearly another half-century before Pfizer transformed into the pharmaceutical leader we know today.

Pfizer was valued at $2 million at the time of its incorporation, and its 20,000 shares would remain in private hands for another 42 years. By 1906, the year of founder Charles Pfizer's death, the company was doing $3 million in annual sales, but this was before either of its two greatest breakthroughs in its path to pharmaceutical greatness. Those breakthroughs occurred first in 1919, when a Pfizer chemist developed an artificial means to produce vitamin C, and then in 1944, when the company used methods perfected for vitamin C to mass-produce penicillin. Pfizer reported net income of $2.3 million for that year on sales of $24.4 million. Six decades later, Pfizer reported annual net income of $11.4 billion on sales of $52.5 billion. Along the way, Pfizer set the standard for pharmaceutical marketing, from its early reliance on physician-focused sales teams to its groundbreaking public advertising of Viagra.

Precious hamburgers (and the stock is pretty valuable, too)
(NYSE:MCD) went public on April 21, 1965. Although only a decade removed from Ray Kroc's first franchise, McDonald's was already growing rapidly, and at the time of its IPO there were more than 700 franchises scattered across the United States. It continued to grow rapidly, passing $1 billion in sales seven years after its IPO and reaching 10,000 global locations by 1988. Four decades after its IPO, McDonald's made up about 2.5% of all the restaurants in the United States -- but it accounted for about 7.3% of total U.S. restaurant revenue. It should come as no surprise, then, that the company's stock was one of the market's best performers during those four decades.

All roads lead to Rome
Some empires are built on the foundations of history, but others stretch so far back that only myth can give them proper form. Rome is such an empire, one that remains the touchstone for Western civilization more than 2,000 years after its creation. When was Rome created? According to legend, Romulus and Remus, twin orphans, founded Rome on April 21, 753 B.C. 

The twins Romulus and Remus were the sons of war god Mars by the daughter of a pre-Roman Latin king. Abandoned in the Tiber river, the two were instead rescued by a she-wolf, who nursed them until they were discovered by a shepherd. On reaching manhood, the twins would prove adept leaders, and with a band of followers they would found Rome on the banks of the river where they had been rescued. Soon, Romulus and Remus quarreled over the exact location where the city ought to be founded, and Romulus killed his brother with a stone.

Thus we have the Roman empire, and not the Reman empire, which would grow over time to become the largest and most institutionally durable empire in Europe. Many elements of our modern economy -- although greatly expanded over the centuries -- trace their history to the Roman Empire, including banks, which arose in a manner like their present form in Renaissance Italy, nearly two millennia after the founding of Rome.

One hundred million!
General Motors (NYSE:GM) was near the absolute height of its power when it passed a truly momentous milestone on April 21, 1967. That day, the 100 millionth domestically produced GM automobile rolled off its assembly line. GM was by that point the embodiment of American industry -- only five years earlier, it had produced its 75 millionth domestic car, in a year when just over half of all cars made in the United States bore one of GM's nameplates.

The event, however, was somewhat marred by ongoing contract negotiations with the United Auto Workers, which took up the lion's share of auto-industry reporting that day. Despite this labor unrest, the Chicago Tribune managed to offer a concise chronology of GM's rise to dominance, and a bit of background on the eventful vehicle:

The 100 millionth vehicle was a Chevrolet Caprice coupe, equipped with just about every option offered, from air conditioning to automatic speed control. It will be shipped to the Alfred P. Sloan Jr. museum in Flint, Mich., where it will be pit on permanent display. ...

The pace at which GM approached the 100 million mark has quickened in recent years. From the first car (a Cadillac) in 1908, it took more than 10 years to build the millionth car (an Oldsmobile) in 1919. The five millionth was a Pontiac built in 1926. The 25 millionth was a Chevrolet assembled in 1940. Another Chevrolet was the 50 millionth in 1954.

Fool contributor Alex Planes holds no financial position in any company mentioned here. Add him on Google+ or follow him on Twitter, @TMFBiggles, for more insight into markets, history, and technology.

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