How did Meryl Streep become Will Smith?

While the back-to-back successes of “Independence Day” and “Men in Black” led Will Smith to famously claim that he “owned” the July 4 weekend — that was before “Wild Wild West,” of course — the actor has since gone on to focus on year-end Oscar-bait movies like “The Pursuit of Happyness” and “Seven Pounds.”

So who’s the reigning champ of the summer box office, the star who’s gained a reputation as a bankable, can’t-miss proposition while school’s out?

That’d be two-time Oscar-winner Meryl Streep, who just celebrated her 60th birthday and who seems to be on track to have another hot-weather hit on her hands with Nora Ephron’s “Julie & Julia,” which stars Streep as legendary chef Julia Child.

Streep’s rise to box office dominion is unlikely, to say the least: For one thing, she’s a woman over 35, a class of people for whom Hollywood shows all the respect that the Tennessee Valley Authority has for the snail darter.

On top of that, she’s Meryl-frakking-Streep, considered by many to be the greatest living actress in American cinema; her movies are supposed to premiere in Toronto, open on four screens after Thanksgiving and then go slightly wider after she racks up yet another Oscar nomination. Her name shouldn’t even pop up in the same breath as “franchise” or “tentpole” or “sequel” or “Michael Bay.”

But then it’s always the least predictable Hollywood stories that are the most fascinating ones. While sure things like “Land of the Lost” and “Speed Racer” fall by the wayside, Streep has starred in two huge summer hits: “The Devil Wears Prada” (2006) took in almost $125 million domestically and another $200 million overseas, while the juggernaut known as “Mamma Mia!” (2008) earned more than $600 million worldwide, becoming the highest-grossing film in the United Kingdom along the way.

There’s certainly no formula behind what works and what doesn’t in the show business, but I would venture to guess there’s a concrete strategy behind Streep’s climb to the top of the summer sweepstakes:

Don’t be afraid to get silly. Streep made her bones playing super-serious roles in super-serious movies like “Sophie’s Choice,” “The French Lieutenant’s Woman” and “A Cry in the Dark,” so it’s all the more enjoyable for audiences, I think, to watch her loosen up and have some fun.

While early attempts at comedy like “She-Devil” and “Death Becomes Her” didn’t click with viewers — although both are terrific and underrated movies — people loved watching her devour the scenery as a corporate Cruella DeVille in “Prada.” Similarly, her goosey, ebullient Julia Child in “Julie & Julia” is already winning over critics and will probably do the same for ticket-buyers.

“Mamma Mia!” gave Streep the opportunity to cavort around in silly outfits and sing ABBA tunes — not to mention that mid-air split, a challenging move at any age — and it humanized her to people who wouldn’t have been caught dead paying to see “The Hours.” It’s sort of like watching your stuffy professor get tipsy and dance on a table at a graduation party.

Throw in something for the young people. Streep has been very shrewd about selecting vehicles with a multi-generational cast. Any under-25s who didn’t know her pre-“Prada” were instead enticed into the theater by the prospect of Anne Hathaway wearing a parade of designer outfits, while “Mamma Mia!” included the Amanda Seyfried-Dominic Cooper romance to inure the Gen Y-ers from the fact that the film’s main characters were all over 50.

1. More Entertainment stories
   1. Will Smith shines in 'Men in Black III'
      

      REVIEW: If you're not a fan of Will Smith's smooth-talking Agent J in the "Men in Black" franchise, don't see the third mo...

   2. Can WWII film hidden by Army help veterans?
   3. Happy 35th anniversary, 'Star Wars'!
   4. Tim McGraw giving homes, hope to veterans
   5. Phillip Phillips has a double double name name

“Julie & Julia” has Streep sharing not just billing but the title itself with Amy Adams (her “Doubt” co-star); the latter’s storyline of blogging and marital doubt and squeamishness over aspic is as new-millennial as Streep-as-Child’s efforts to import French cuisine to American kitchens are mid–20th century.

There’s something to be said for high concept. While earlier Streep vehicles like “Out of Africa” or “Ironweed” didn’t necessarily lend themselves to a one-line plot description, the “Prada”-“Mamma”-“Julia” troika all have stories that can pretty much be gleaned by one glance at the poster, making them perfect fare for a season in which it’s just too darn hot to do much thinking.

It’s not like Streep has walked away from complicated fare entirely — the last decade has seen her in a variety of challenging films, including “A Prairie Home Companion,” “Adaptation,” “The Manchurian Candidate” and the flawed-but-ambitious “Rendition” and “Evening” — but she’s kept her career alive by very cannily choosing audience-pleasers. (Would that Nicole Kidman had as good an eye for her multiplex movies as she does for arthouse fare.)

Streep’s latter-day successes represent a triumph for her, of course, but they also stand as an argument against lazy corporate thinking. Women aren’t a viable summertime audience, you say? Young people don’t want to see a film featuring an older actress? Ladies over 40 can’t open movies?

Wrong, wrong, wrong.

Long may she reign.