When schedules revealed there was no tentpole for most of June, studios and theater owners quietly worried that traffic would take a dive. And they were right, sort of.

There’s been a dip in moviegoing in each of the past three weekends, but not enough to drag down the bottom line. Much of that is thanks to breakout hits “The Hangover” and “Up,” as well as booming weekday biz.

Summer revenues to date are running essentially even with last year, although attendance is running behind by 3%. The slight downturn is narrowing overall gains made this year in revenue and attendance, but those numbers routinely fluctuate.

Through Sunday, summer B.O. revs stood at $1.46 billion, compared to $1.47 billion last year.

Year-to-date, domestic revenues are up 9.5% over last year, or $4.53 billion vs. $4.14 billion. Attendance is up an impressive 6%.

At other points, revenues have been up as much as 13%, and attendance 7% or 8%.

Now comes the hard part: Can the remaining summer tentpoles and mid-range pics keep the summer afloat?

Most think Hollywood has a strong shot, between Paramount’s “Transformers: Revenge of the Fallen” (June 24), 20th Century Fox’s 3-D toon “Ice Age: Dawn of the Dinosaurs” (July 1) and Warner Bros.’ “Harry Potter of the Half-Blood Prince” (July 15).

The original “Transformers” grossed $319.2 million domestically; “Ice Age: The Meltdown,” $195 million; and “Harry Potter and the Order of the Phoenix,” $292 million. Sequels generally do better than previous installments.

There also are a number of mid-range pics that could wield plenty of box office might, considering that much of the success of 2009 is due to mid-size films that have over- performed, such as Fox’s “Taken,” Universal’s “Fast and Furious” and now, “Hangover,” which jumped the $100 million mark in its first 10 days, the first R-rated comedy ever to do so.

Upcoming summer films falling outside the tentpole category include “Bruno” and Johnny Depp topliner “Public Enemies,” both from Universal, as well as Sony’s romantic comedy “the Ugly Truth,” Summit’s “Band Slam” and Sony’s “District Nine.”

“The volume and size of product would suggest it is possible, no question about it. There’s a lot of money left,” one studio distrib said. “Who would have thought ‘Hangover’ or ‘Up’ would do the business they have?”

But the summer can’t afford too many more disappointments, the exec said, noting that there have already been two underachievers: Universal’s “Land of the Lost” and Par’s “Imagine That.”

The general spike in moviegoing began last fall in the wake of the economic meltdown, as auds flocked to a relatively inexpensive form of entertainment. The summer frame will be an important test of whether the B.O.’s growth spurt was a knee-jerk reaction to the gloomy economic news or a long-term trend.