The U.S. dockworkers who went on strike early Tuesday are just the latest unionized group to back their demands for better contracts by walking off the job to illustrate their value to both the national economy, and their employers' bottom line.

Unions representing auto workers, actors, hotel housekeepers and aircraft assembly workers all called strikes as organized labor made itself heard over the past year. Members argued they made the sacrifices their companies asked of them during the pandemic and rough economic patches, and now it's time to catch up, particularly after several years of heightened inflation.

Between 2022 and 2023, the number of work stoppages rose 9% to 466 strikes and four lockouts, according to figures maintained by Cornell University's ILR School. However, the number of workers involved in work stoppages, approximately 539,000, was more than double than the previous year, according to the school's research.

A database maintained by Cornell and the School of Labor and Employment Relations at the University of Illinois Urbana-Champaign recorded 250 strikes and other labor actions in 2024 as of Monday.

Here's a look at some recent showdowns between companies and organized labor

U.S. ports and the International Longshoremen's Association

Dockworkers at 36 ports from Maine to Texas hit picket lines early Tuesday, the first strike for them in decades, over wages and automation even though progress had been reported in contract talks. The contract between the ports and about 45,000 members of the International Longshoremen's Association expired at midnight.

The alliance said it had increased its offer to 50% raises over six years and it pledged to keep limits on automation in place from the old contract. The alliance also said its offer tripled employer contributions to retirement plans and strengthened health care options. In a statement early Tuesday, the union said it rejected the alliance's latest proposal because it "fell far short of what ILA rank-and-file members are demanding in wages and protections against automation." The two sides had not held formal negotiations since June.

Workers at the Port of Philadelphia walked in a circle outside the port and chanted "No work without a fair contract." The union, striking for the first time since 1977, had message boards on the side of a truck reading: "Automation Hurts Families: ILA Stands For Job Protection."

If drawn out, the strike will force businesses to pay shippers for delays and cause some goods to arrive late for peak holiday shopping season — potentially impacting delivery of anything from toys and artificial Christmas trees to cars, coffee and fruit.

Boeing and the International Association of Machinists

Aircraft assembly workers walked off the job at Boeing factories near Seattle and elsewhere on Sept. 12 after union members voted overwhelmingly to reject a proposed contract and go on strike. Boeing and negotiators from the International Association of Machinists and Aerospace Workers have held three bargaining sessions alongside federal mediators. The company presented a revised contract last week, but the union refused to present it for a vote after surveying its members, who said it failed to meet their wage and pension demands.

Video games and SAG-AFTRA

Earlier this month video game performers reached agreements with 80 individual games that have signed interim or tiered budget agreements with the performers' union and accepted the artificial intelligence provisions they have been seeking.

The performers had been striking for over a month.

Members of the Screen Actors Guild-American Federation of Television and Radio Artists began striking in July after negotiations with game industry giants that began more than a year and a half ago came to a halt over AI protections.

The interim agreement secures wage improvements, protections around "exploitative uses" of artificial intelligence and safety precautions that account for the strain of physical performances, as well as vocal stress. The tiered budget agreement aims to make working with union talent more feasible for independent game developers or smaller-budget projects while also providing performers the protections under the interim agreement.

Las Vegas resorts and Culinary Workers Union

Last month, thousands of hospitality union workers on the Las Vegas Strip reached a tentative deal with the Venetian and Palazzo resorts, a first for employees at the sprawling Italian-inspired complex that opened 25 years ago.

The Culinary Workers Union announced on the social platform X that the deal came together after a year of negotiations. It covers over 4,000 hotel and casino workers, from housekeepers and cocktail servers to bartenders and porters.

Bethany Khan, a union spokesperson, said the deal mirrors the major wins secured in recent contracts awarded to 40,000 hospitality workers at 18 Strip properties owned or operated by casino giants MGM Resorts International, Caesars Entertainment and Wynn Resorts.

Those wins included a 32% pay increase over five years, housekeeping workload reductions and improved job security amid advancements in technology and artificial intelligence.

The bump in pay under those contracts will amount to an average $35 hourly wage by the end of the contracts, according to the union. Workers at these properties were making about $26 hourly with benefits before winning their latest contracts in November.

Hotel chains and UNITE HERE

More than 10,000 workers at 25 hotels across the U.S. staged a Labor Day weekend strike to amplify their demands for higher pay, fairer workloads and the reversal of COVID-era cuts. The majority of the striking housekeepers and other hospitality workers represented by the UNITE HERE union stayed off the job for a few days. On Sept. 24, about 2,000 unionized workers at Hawaii's largest resort, the Hilton Hawaiian Village Waikiki Beach Resort, joined another couple thousand hotel workers who remained on strike at Hilton, Hyatt and Marriott hotels in Honolulu, San Diego and San Francisco, according to the union.

Kaiser Permanente and health care workers

Unions representing 85,000 health care workers reached a tentative agreement with industry giant Kaiser Permanente in October 2023 following a strike over wages and staffing levels.

The deal included setting minimum hourly wages at $25 in California, where most of Kaiser's facilities are located, and $23 in other states. Workers would also see a 21% wage increase over four years.

The lead up to the agreement included a three-day strike involving 75,000 workers in multiple states.

The agreement also included protective terms around subcontracting and outsourcing, as well as initiatives to invest in the current workforce and address a staffing crisis.

Automakers and UAW

Late last year, the United Auto Workers union overwhelmingly ratified new contracts with Ford and Stellantis, along with a similar deal with General Motors, that would raise pay across the industry and force automakers to absorb higher costs.

The agreements, which run through April 2028, ended contentious talks that began in the summer of 2022 and led to six-week-long strikes at all three automakers.

The new contract agreements were widely seen as a victory for the UAW, though Ford's top executive said the company will rethink where it will build cars in the future. The companies agreed to dramatically raise pay for top-scale assembly plant workers, with increases and cost-of-living adjustments that would translate into 33% wage gains.

Top assembly plant workers were to receive immediate 11% raises and would earn roughly $42 an hour when the contracts expire in April of 2028.

Under the agreements, the automakers also ended many of the multiple tiers of wages they had used to pay different workers. They also agreed in principle to bring new electric-vehicle battery plants into the national union contract.

UPS and Teamsters

UPS workers that are members of the Teamsters union approved a tentative contract with the package delivery company last year before hitting the picket lines as they had vowed to do. The run up to the approval was not smooth though, with contentious labor negotiations that threatened to disrupt package deliveries for millions of businesses and households nationwide.

After negotiations broke down in early July 2023, Atlanta company reached a tentative contract agreement with the Teamsters just days before an Aug. 1 deadline.

At the time the agreement was struck, full- and part-time union workers were set to get $2.75 more per hour in 2023, and $7.50 more in total by the end of the five-year contract. Starting hourly pay for part-time employees also got bumped up to $21, but some workers said that fell short of their expectations.

UPS said at the time that by the end of the new contract, the average UPS full-time driver would make about $170,000 annually in pay and benefits. It was not clear how much of that figure benefits accounted for.

As part of the deal, the delivery company also agreed to make Martin Luther King Jr. Day a full holiday, end forced overtime on drivers' days off and stop using driver-facing cameras in cabs, among a host of other issues. It eliminated a two-tier wage system for drivers and tentative deals on safety issues were also reached, including equipping more trucks with air conditioning.

Hollywood studios and SAG-AFTRA

Hollywood's actors voted to ratify a deal with studios in December 2023 that ended their strike after nearly four months, bringing an official finish to a labor strife that shook the entertainment industry for most of last year.

Members of the Screen Actors Guild-American Federation of Television and Radio Artists approved a three-year contract.

Control over the use of artificial intelligence was the most hard-fought issue in the long, methodical negotiations. The contract called for a 7% general pay increase with further hikes coming in the second and third years of the deal.

The agreement also included a hard-won provision that temporarily derailed talks: the creation of a fund to pay performers for future viewings of their work on streaming services, in addition to traditional residuals paid for the showing of movies or series.