Surge in visitors at Disney's California Adventure, Universal Studios Big investments at Disney's California Adventure Park and Universal Studios Hollywood seem to have paid off. California Adventure Park, the once-struggling Anaheim park, welcomed 7.8 million visitors last year, a 22.6% increase over the previous year, according to the annual theme part attendance estimate by the engineering and consulting firm Aecom and Burbank-based Themed Entertainment Assn. The surge came the same year that Disney unveiled a $1.1-billion makeover of the park, including the construction of Cars Land, the biggest expansion since California Adventure opened in 2001. Meanwhile, Universal Studios Hollywood hosted 5.9 million visitors, a 15% increase in attendance over 2011, according to the Aecom estimate. The rise in guests came as the park opened Transformers: The Ride 3D, a high-tech attraction that was estimated to cost about $100 million. Disneyland, which opened no major new attractions last summer, welcomed nearly 16 million visitors, a 1.1% drop compared with 2011, according to the estimate. The most popular theme park in the country, Walt Disney World in Florida, had 17.5 million visitors in 2012, a 2.3% increase, according to the Aecom estimate. Disneyland and Universal Studios Hollywood do not release annual attendance numbers. L.A. posts record tourist numbers in 2012 How easy is it to visit the U.S.? Two surveys disagree Well-heeled theme park visitors get a thrill from VIP treatment