Summer movie admissions wound up eking out a 1% gain over 2010, according to the National Assn. of Theater Owners, thanks to a final domestic summer B.O. tally of $4.4 billion. Higher 3D ticket prices helped the U.S. box office deliver its highest summer haul ever, yet admissions were still down 5% from 2009, when B.O. hit the previous summertime record of $4.34 billion.

Ticket sales in the U.S. reached 546 million vs. 540 million in 2010, based on an average of second ($7.88) and third-quarter ($7.71) average ticket prices. In 2009, box office recorded 577 million admissions, with a second/third-quarter average ticket price of $7.51. That year, however, benefited from an extra weekend (summer B.O. is calculated from the first full weekend in May through Labor Day).

The ticket sales tally was nearly flat in part since average domestic ticket prices hit an all-time high during the second quarter at $8.06. That’s mostly because of adult-skewing R-rated comedies, led by “The Hangover Part II” and “Bridesmaids,” and 3D tentpoles, including “Harry Potter and the Deathly Hallows: Part 2” and “Transformers: Dark of the Moon.”

But the slight uptick in admissions shows the box office is at least staying the course.

“There’s a constant fluctuation of product and how much time it has in the market,” said NATO director of media and research Patrick Corcoran. “Certainly, we would like admissions to grow, but it’s a good sign that we can still grow revenues when admissions are stagnant.”

NATO prexy John Fithian added: “In the midst of 9% unemployment and a continuing weak economy, it is striking that the movie theater industry can continue to grow revenues and admissions.”

The strength of the summer season has reduced a near 21% year-over-year B.O. deficit at the end of the first quarter to a discrepancy of just 3% below 2010. This year marks the fifth straight summer in which Stateside totals have exceeded $4 billion.

“In a weak economy or strong, the movie theater remains the first and most affordable choice in out-of-home entertainment,” Fithian said.