We all descended on Boston last week -- Democratic delegates, party consultants, political junkies and journalists -- for what often seemed more a sales convention than a political convention. If you doubt the analogy, consider this: In the 2000 election Americans were showered with 245,743 TV spots for George W. Bush and Al Gore, says the University of Wisconsin Advertising Project. Spending on TV spots this year will probably be double the 2000 level or higher.

Politics has adopted all the tools of modern merchandising -- advertising, polling, telemarketing and demographic targeting. Conventions, which once selected a party's candidate, are now part of the marketing plan. Deliberately drained of controversy, they aim to sharpen the campaign's message and to reward fundraisers and the party faithful. By one count, the Democratic convention had more than 200 parties, receptions, seminars and golf tournaments. "This is a way to fire up your troops," says Terry McAuliffe, chairman of the Democratic National Committee.

In old-time conventions, state party bosses controlled their delegates and haggled over candidates. From 1840 to 1952, barely half the candidates won on the first ballot, reports political scientist Byron Shafer of Wisconsin. In 1896 the Democrats started with 14 candidates; William Jennings Bryan prevailed on the fifth ballot. The longest marathon occurred in 1924, when Democrats took 103 ballots and 16 days to nominate John W. Davis, who was trounced by Calvin Coolidge. The last time conventions truly selected candidates was 1952. Adlai Stevenson won on the third ballot and Dwight Eisenhower on the first -- but only after a last-minute switch by the Minnesota delegation.

Politics is following the lead of business. Local markets went national. In a recent book ("Birth of a Salesman"), historian Walter Friedman of Harvard University noted that salesmanship in the United States started with peddlers. They "carried trunks filled with goods" -- buttons, clocks, pots, cloth -- from farm to farm. Sales were closed face to face. But by the late 19th century, companies were advertising to promote national brands and mass markets. One of the leaders was a company run by Henry Heinz (the source of Teresa Heinz Kerry's fortune). It sold ketchup, canned fruits and vegetables.

As political scientist Shafer writes, politics evolved similarly. Television spoke to mass markets. Presidential primaries weakened political bosses; so did the loss of patronage jobs for loyal party workers. Personal politics slowly became impersonal marketing. Power passed from bosses to marketers: technocrats who crafted sound bites, studied polling data and made advertising buys. Conventions retained some drama into the 1980s. Feuds broke out over party platforms. Challengers (say, Reagan in 1976) threatened front-runners. But conventions increasingly became marketing exercises.

Fittingly, the first presidential TV spots ran in 1952. One series was called "Eisenhower Answers America."

Woman: You know what things cost today. High prices are just driving me crazy.

Eisenhower: Yes, my Mamie [his wife] gets after me about the high cost of living. It's another reason why I say it's time for a change, time to get back to an honest dollar and an honest dollar's worth.

Now many TV spots run on local stations in contested "battleground" states. So far in 2004, the top 10 local markets for presidential advertising include four in Ohio (Toledo, Dayton, Columbus and Cleveland), reports the Wisconsin Advertising Project. The other six are in Missouri (Kansas City and St. Louis), Oregon (Portland), Pennsylvania (Erie), Nevada (Las Vegas) and Michigan (Detroit). By merging data files on voting behavior and TV-viewing habits, media buyers know how audiences differ. "[Dave] Letterman skews more Democratic, while [Jay] Leno is more Republican," says one consultant.

Of course, the marketing revolution poses profound questions about politics and democracy. One paradox is that as politics became marketing, people treated it that way. Arguably, cynicism increased. Voters became more dismissive of political rhetoric and ignored TV spots. Candidates and parties have to advertise more for the same effect. There's a constant quest to find new ways to reach voters. "I can send out 700,000 e-mails an hour," says the DNC's McAuliffe. The DNC has a database of 175 million names and has disgorged 75 million pieces of direct mail this year -- compared with 10 million for the entire 1990s.

The larger question involves democracy. By itself, the money needed to run modern campaigns isn't corrupting. The sheer number of even big contributors dilutes the influence of individual contributors. The real issue is whether politics is more subject to manipulation. Ken Goldstein, director of the Wisconsin Advertising Project, says that people's party identities, their views on issues, and the economy still determine far more than 90 percent of voting decisions. Advertising operates on the fringes. Every close election inevitably poses this question: Did the result reflect what voters wanted -- or the cleverest marketing campaign?