Florida governor Ron DeSantis spoke to Rush Limbaugh last fall at a gala dinner for the National Review Institute. The radio host was there to receive the William F. Buckley Jr. award. "He actually gave me one of the greatest compliments I've ever had," Limbaugh told his audience the next day. "He listed five great conservatives and put me in the list." DeSantis's pantheon: William F. Buckley Jr., Ronald Reagan, Antonin Scalia, Clarence Thomas, and Limbaugh.

Good list. No media figure since Buckley has had a more lasting influence on American conservatism than Limbaugh, whose cumulative weekly audience is more than 20 million people. Since national syndication in 1988, Limbaugh has been the voice of conservatism, his three-hour program blending news, politics, and entertainment in a powerful and polarizing cocktail. His shocking announcement this week that he has advanced lung cancer, and his appearance at the State of the Union, where President Trump awarded him the Presidential Medal of Freedom, are occasions to reflect on his impact.

It's one thing to excel in your field. It's another to create the field in which you excel. Conservative talk radio was local and niche before Limbaugh. He was the first to capitalize on regulatory and technological changes that allowed for national scale. The repeal of the Fairness Doctrine in 1987 freed affiliates to air controversial political opinions without inviting government scrutiny. As music programming migrated to the FM spectrum, AM bandwidth welcomed talk. Listener participation was also critical. "It was not until 1982," writes Nicole Hemmer in Messengers of the Right, "that AT&T introduced the modern direct-dial toll-free calling system that national call-in shows use."

Limbaugh made the most of these opportunities. And he contributed stylistic innovations of his own. He treated politics not only as a competition of ideas but also as a contest between liberal elites and the American public. He added the irreverent and sometimes scandalous humor and cultural commentary of the great DJs. He introduced catchphrases still in circulation: "dittohead," "Drive-By media," "feminazi," "talent on loan from God."

The template he created has been so successful that the list of his imitators on both the left and right is endless. Even Al Franken wanted in on the act. Dostoyevsky is attributed with the saying that the great Russian writers "all came out of Gogol's ‘Overcoat.'" Political talk show hosts came out of Limbaugh's microphone.

Limbaugh's success prefigured more than the rise of conservative radio. His two bestsellers, The Way Things Ought to Be (1992) and See, I Told You So (1993), were the leading edge of the conservative publishing boom. And his television program, The Rush Limbaugh Show, produced in collaboration with Roger Ailes, was a forerunner of the opinion programming on Fox News Channel. "I had to learn how to take being hated as a measure of success," he told a Boy Scouts awards dinner in 2009. "Nobody's raised for that. And the person that taught me to deal with this and to remain psychologically healthy was Roger Ailes."

Limbaugh is not fringe. His views fit in the conservative mainstream. He idolizes Buckley. "He was a fundamental individual in helping me to be able to explain what I believed instinctively, helping me to explain it to others," Limbaugh said last year. The ideas are the same but the salesman is different. Limbaugh is Buckley without the accent, without the Yale credentials, without the sailboat and harpsichord. Limbaugh is a college dropout from Cape Girardeau, Missouri, who spends Sundays watching the NFL and speaks in plain language. His background connects him to the audience—and to the increasingly working-class Republican voter.

Limbaugh entered stage right just as Ronald Reagan made his exit. He took from Reagan the sense that America's future is bright, that America isn't broken, just its liberal political, media, and cultural elites. "He rejected Washington elitism and connected directly with the American people who adored him," Limbaugh said after Reagan's death. "He didn't need the press. He didn't need the press to spin what he was or what he said. He had the ability to connect individually with each American who saw him." The two men never met.

Limbaugh assumed Reagan's position as leader of the conservative movement. In a letter sent to Limbaugh after the 1992 election, Reagan wrote, "Now that I've retired from active politics, I don't mind that you have become the Number One voice for conservatism in our Country. I know the liberals call you the most dangerous man in America, but don't worry about it, they used to say the same thing about me. Keep up the good work. America needs to hear ‘the way things ought to be.'"

In a long and evenhanded cover story in 1993 by James Bowman, National Review pronounced Limbaugh "the leader of the opposition." Bowman quoted R. Emmett Tyrrell Jr., editor of The American Spectator. "We need to have people who can dramatize ideas," Tyrrell said. "You need that literary spark. Luigi Barzini had it; Buckley has it. And, though he's a great talker rather than a great writer, Rush has it too."

More than a decade later, after the Republican defeat in 2008, Limbaugh once again stepped into the breach. The media likened Barack Obama to FDR. Republicans wavered. Should they cooperate with President Obama in building a "New Foundation" for America? Limbaugh gave his answer on January 16, 2009. "I've been listening to Barack Obama for a year and a half," he said. "I know what his politics are. I know what his plans are, as he has stated them. I don't want them to succeed." Limbaugh said he hoped Obama failed. "Liberalism is our problem. Liberalism is what's gotten us dangerously close to the precipice here. Why do I want more of it?" The monologue, and the speech he delivered to the Conservative Political Action Conference in Washington, D.C., a month later, became a sensation. They set the tone for the Tea Party and Republican victories in 2010 and 2014.

Limbaugh did not mock Trump when the businessman announced his presidential campaign in June 2015. "This is going to resonate with a lot of people, I guarantee you, and the Drive-Bys are going to pooh-pooh it," he said. He spent the primary reminding listeners of the importance of defeating Hillary Clinton. Trump was not an ideological candidate, he said. Trump was a missile aimed at the establishment. If ideology matters, then you should vote for Ted Cruz. "If conservatism is your bag, if conservatism is the dominating factor in how you vote," Limbaugh said in February 2016, "there is no other choice for you in this campaign than Ted Cruz, because you are exactly right: This is the closest in our lifetimes we have ever been to Ronald Reagan." But, Limbaugh added, the feeling in the country might be so anti-establishment that Trump's unusual coalition could win the presidency. It did.

To say that Limbaugh supports the president would be an understatement. Last December he introduced the president at a Turning Point USA summit. He mentioned a recent encounter on a golf course. Someone told him it is hard to defend President Trump. "I said, ‘What? Hard to defend the president? It's one of the easiest things in the world to do.' President Trump does not need to be defended." The crowd cheered. A few seconds later Limbaugh said, "How do you defend Donald Trump? You attack the people who are attempting to destroy him. They're trying to destroy you. They're trying to transform this country into something that it was not founded to be."

Bold, brash, divisive, funny, and amped up, President Trump's style is similar to a shock jockey's. His presidency is another reminder of Limbaugh's staying power. The American right has been molded in his anti-elitist, grassroots, demotic, irreverent, patriotic, hard-charging image. Rush Limbaugh is not just a broadcaster. He defines an era.