Artists are seldom appreciated in their own time. The same can be true for U.S. presidents.

Nearly 100 years after leaving office, Theodore Roosevelt is more popular than ever. While biographers in his day sneered at him as a showman who was all talk and no action, he is now seen as one of America's most consequential presidents.

Worshiped by fellow Republicans such as Sen. John McCain of Arizona, Roosevelt is also admired by Democrats. Bill Clinton kept a bust of T.R. on his desk in the Oval Office.

That popularity is one reason T.R. recently landed on the cover of Time magazine. The publication put together a complimentary series of articles about the nation's 26th president, including an essay by presidential adviser and history buff Karl Rove on the lessons Americans could learn from Roosevelt.

Personally, I've always thought that the public's fascination with Teddy Roosevelt had a lot to do with his maverick ways. Elected with the support of the business community, he broke up unfair monopolies and pushed for food inspection and workplace safety laws. A hero for his exploits leading the Rough Riders in the Spanish-American War, he was also the first American to be awarded the Nobel Peace Prize for helping end the Russo-Japanese War. And although he came into office at a time when the United States was expanding and amassing great wealth, he made his mark as an environmentalist and conservationist determined to preserve natural resources so as not to — as he said — "rob, by wasteful use, the generations that come after us."

But Teddy's independent streak is only part of the reason he's so popular, insists Dan Murphy, professor of American history at Hanover College. A Roosevelt aficionado, Murphy is writing a book on World War I-era intellectuals in which T.R. figures prominently.

For Murphy, a big reason for Roosevelt's staying power is that he could "simultaneously look in two different directions." Assuming the presidency in 1901, he had one foot in the 19th century, another in the 20th.

"He's the first modern president and sort of created the 20th-century presidency with the bully pulpit, the first progressive president who is taking us into the 20th century," Murphy told me. "And yet he's the cowboy. He's the fellow who takes people back to the frontier and all the virtues associated with that."

Roosevelt was also full of contradictions. Here was this brash, vibrant young president who was macho before Americans even knew what macho was. And yet he was also a serious writer, scientist and historian.

Some of his thinking led him onto dangerous ground. According to Murphy, Roosevelt developed a concern over "race suicide" — the idea that, if the older-stock Americans didn't keep pace with the birthrates of, say, Irish Catholic immigrants, the privileged class could meet its demise.

Immigrants? Birthrates? Let's see, where have I heard that line before?

Roosevelt was a major proponent of assimilation and a devotee of the Americanization movement, which pressured foreigners to learn English and adopt American values and customs. In an oft-quoted speech delivered shortly before his death in 1919, he blasted the idea of "hyphenated Americans" and worried that the country could be destroyed by "squabbling nationalities."

Today, many who hold similar beliefs obsess over whether Hispanic immigrants are blending into society as quickly as they should be.

But in Roosevelt's day, those concerns were mostly reserved for German-Americans. That didn't necessarily make him a bigot, Murphy insisted. For Roosevelt, the ex-soldier, it was less about nativism than nationalism and patriotism — especially after the outbreak of World War I.

Eventually, Murphy acknowledged, Roosevelt "becomes pretty vehemently anti-German." But, for the ex-soldier, it's all about the war. "Once the United States starts fighting these people," Murphy said, "then they're the enemy."

Many historians agree that Roosevelt invented the modern presidency, where the man shapes the office and not the other way around. It didn't hurt that he had a legendary enthusiasm for life. As T.R. noted at one point, "While president, I have been president — emphatically."

Rove picks up on that thread, writing that Roosevelt's life was "characterized by passion and zest and a drive to achieve great things."

I get it now. In that respect, T.R. was the very embodiment of America — not just in his time, but for all time. It's no wonder that one still can't get enough of the other.

Ruben Navarrette Jr. is a columnist and editorial board member of The San Diego Union Tribune. He is the author of "A Darker Shade of Crimson: Odyssey of a Harvard Chicano." Reach him at ruben.navarrette@uniontrib.com.