The city of Los Angeles is on strike. A growing number of unions seeking improved conditions for their employees are halting movie productions in the city, holding up hotel business, potentially disrupting supply chains, and slowing down the airport.

Today, 11,000 Los Angeles city workers are joining Hollywood actors, among others on the picket lines, according to the union that represents many of the city's public sector staff. The strike is the first by LA city workers in more than 40 years.

The effects are city-wide: sanitation workers, lifeguards, custodians at public schools, LAX airport shuttle drivers and mechanics, crane operators and boat captains at the city's ports are among the workers who are planning to strike -- or who have already walked off the job.

Why are city workers going on strike?

The heatwave and seriously short staffing -- there are hundreds of job vacancies in the city -- are causing union members to be "at their breaking point," David Green, president of SEIU Local 721, told CNN.

SEIU 721 is the union representing more than 95,000 workers in Southern California. Members voted to authorize the strike only after "repeated labor law violations" by Los Angeles city management, according to the union.

Usually, a lot of what their members do "goes unnoticed," said Green. "But on Tuesday, we're going to make sure everybody notices."

Who else is on strike?

It comes amid a wave of union activity in the city and across the country.

Los Angeles is the epicenter of Hollywood actors' and writers' strikes that have brought the entertainment industry to a standstill. The union representing 15,000 hotel workers, including cooks, room attendants, and front desk agents, has staged a series of rolling strikes in the city since the start of July. In Northern California, more than 4,500 San Jose city workers announced they will stage a three-day strike beginning Tuesday, August 15, demanding pay that keeps up with living costs.

Recent labor unrest has affected more than just California: thousands of United Auto Workers union members are threatening to strike in September absent a labor agreement with Detroit's big three automakers: Ford, General Motors, and Stellantis.

A massive economic disruption was narrowly avoided last month when the Teamsters union reached a tentative agreement with UPS on a new contract, potentially avoiding a strike by more than 300,000 UPS workers that would have potentially cost the US economy billions of dollars. The Teamsters membership now has to approve the contract by vote for the chance of a strike to be fully over.

What do politicians have to say?

"Fortunately, we have a really terrific mayor that's new to Los Angeles," Green said. "We have some great city council members, but we have some real out of touch administrators that didn't want to come to the table."

Los Angeles Mayor Karen Bass said in a statement that the city has been bargaining with the union in good faith.

"City workers are vital to the function of services for millions of Angelenos every day and to our local economy. They deserve fair contracts, and we have been bargaining in good faith with SEIU 721 since January. The City will always be available to make progress 24 hours a day, 7 days a week," she said.

Green said that Bass supports working people and understands the immediacy, however, workers are the ones who feel the immediacy as they are on the front lines.

What does this mean for Angelenos?

For the Angelenos, a strike could mean slower service across the city.

Los Angeles city departments are bracing for the impact of today's work stoppage and attempting to mitigate disruptions to city operations.

For example, LAX has warned passengers to allow extra time to travel to and from the airport on Tuesday. "LAX is working diligently with our airport partners to ensure that our operations will continue as close to normal as possible and to mitigate the impacts of the work action on our guests," Dae Levine, a Los Angeles World Airports spokesperson, told CNN.

The Port of Los Angeles, the busiest port in the United States by container volume and the focal point of many of the country's supply chain disruptions during the pandemic, told CNN that port operations would continue. However, 300 employees at the port are represented by SEIU 721.

-- CNN's Sam Delouya and Nadia Bidarian contributed to this report