Halloween is growing so big, it's scary.
To crank up the fright levels, Universal Studios Hollywood employed directors and producers of creepy movies and television series to help create new attractions for this year's Halloween celebration.
Six Flags Magic Mountain in Valencia, Calif., expanded its annual spook fest by an extra weekend and built its biggest outdoor maze ever, a 40,000-square-foot labyrinth haunted by post-apocalyptic killers.
And for the first time, Warner Bros. Studios jumped into the competition for Halloween fans this year by launching a nighttime tour of the Burbank studio lot, plus a screening of two Warner Bros.-distributed horror films: "The Conjuring" and "The Conjuring 2."
The newest Halloween upgrades at Southern California's theme parks — and others around the country — are a testament to the autumn holiday's freakish growth and profitability.
"Halloween has become high stakes certainly for the biggest theme parks," said Martin Lewison, a business administration professor and theme park expert from Farmingdale State College in New York. "They always have to stay on top, always have to be cutting edge."
He compared the expansion of Halloween events at theme parks to the decision by fast-food giant McDonald's in the 1970s to add breakfast to the chain's meal offerings.
"It's called capital intensity," he said. "You increase by taking your investment and squeezing more money out of it."
Nationwide, more than 300 amusement parks operate Halloween attractions, generating at least $500 million in revenue annually, according to Hauntworld, a website based in St. Louis that promotes businesses with "haunted" or Halloween themes.
At Six Flags Great America in Gurnee, the annual Fright Fest — held on weekends through Oct. 30, as well as on Columbus Day and Halloween — has become increasingly elaborate. And popular. This year it added two new haunted houses and a couple of new shows.
"It's our 25th year," said Dameon Nelson, Great America's director of operations. "The first year, there were cornstalks everywhere, and there were actors throughout the midways, but at that time, it was an event in its infancy. Twenty-five years later, it's a whole different event. You encounter 100 different actors who are there for no other reason than to scare you, and that makes for an amazing experience."
An annual Halloween industry show in St. Louis that began eight years ago in a 50,000-square-foot hall has grown to 250,000 square feet, including booths that sell scary props, ticket-dispensing equipment, lighting and hayride equipment, among other Halloween items, said Larry Kirchner, a spokesman for Hauntworld.
"The number just keeps growing on a level you can't imagine," he said.
Many theme parks charge a separate admission fee to attend the Halloween events that begin in the evening.
Six Flags Magic Mountain allows daytime visitors to stay after dark but they must buy a wristband to enter the individual horror attractions. The tickets range from $40 to more than $200 for a pass that lets visitors avoid the lines.
At Universal Studios Hollywood, Eli Roth, the producer of such horror films as "Hostel," "Cabin Fever" and "The Stranger," was recruited to remake the park's iconic tram ride.
Universal Studios' Halloween Horror Nights runs on select nights through Nov. 5.
Roth compared the Halloween mazes and attractions to live concerts or music festivals where large groups share in the experience.
"You can't replicate the live experience," Roth said. "You just have to make the pilgrimage and be a part of it."
Ryan Murphy, the creator of the "American Horror Story" television series, said he wanted to help build a maze haunted by evil spirits, scenes of gore and freak show actors because he always admired the Halloween attractions at Universal Studios Hollywood.
"For me, if your show is made into a theme park ride, you know you've made it," Murphy said.
The "American Horror Story" maze has been replicated at Universal Studios Orlando in Florida as well.
Murphy calls the attraction a hit. "I peed my pants a couple of times," he quipped, of his experience in the maze.
It's not the first time that Universal Studios has turned to horror masters to boost its Halloween attractions.
In 2012, macabre rocker Alice Cooper helped create a Universal Studios maze. Greg Nicotero, executive producer of the hugely popular "Walking Dead" TV series, helped create a permanent zombie attraction for the park this year.
Although Universal Studios paid licensing fees to use branded images and characters, Roth and Murphy say the real lure was helping to promote their creepy style of horror at a park that draws millions of visitors a year.
Roth, co-founder of an online horror channel, Crypt TV, shows video clips from the channel on the television screens of the tram ride during Halloween Horror Nights.
The trailers for the new season of "American Horror Story" are shown to guests waiting in the queue to go into Murphy's maze.
"It's a way to increase awareness and grow the brand," Murphy said.
At Warner Bros. Studios, the idea for a new Halloween event was sparked last October when the studio displayed a few props from iconic horror movies. The response was so great that studio executives decided to launch two new evening Halloween tours Oct. 28 and Oct. 29 that focus on the horror movies filmed at the studio.
"There are so many fans of the horror genre that it makes sense for us to do it," said Danny Kahn, executive director of Warner Bros. Studio Tours.
For Walt Disney Co.'s theme parks in Anaheim, Calif., Halloween is more playful than frightful.
However, Disney California Adventure is trying to lure big crowds this year by promoting the Twilight Zone Tower of Terror ride's final Halloween. The attraction will be closed in January to be remade featuring Marvel's "Guardians of the Galaxy" characters.
Freelancer Sheryl DeVore contributed to this report.