Hundreds of fast-food workers from McDonald's, Wendy's, Taco Bell, Burger King and other chains walked off the job in a planned strike today aimed at getting the industry to increase wages and allow unionization.

The tactic is part of a larger movement dating back to at least 2012 that's being called the "fight for 15" — a push to get the U.S. federal minimum wage raised to $15 US an hour.

Currently, the U.S. federal minimum wage is $7.25 an hour, the same level since 2009. That works out to about $15,000 a year for a full-time 40-hour-a-week worker.

A disproportionate amount of workers in the fast-food industry are paid at or near the minimum wage. Worse still, organizers of the protest say, they are often limited in their hours worked, which hampers their ability to get benefits.

Protests took place place at fast-food restaurants in 150 cities across America, including Chicago, Detroit and New York. In some places, they were joined by home-care workers. Some workers were handcuffed and detained by police for blocking traffic.

Fast-food minimum wage strikes

The 'Fight for $15' began in earnest in 2013, with multiple demonstrations staged across the U.S. in support of a minimum wage increase. (Jim Young/Reuters)

Officially, the protests are being spearheaded and backed financially by the Service Employees International Union. Previous tactics include showing up with loud sit-in protests at investor meetings of some of the companies involved.

"There's a national movement going on made up of fast-food workers organizing to lift wages so they can provide for their families with pride and dignity," U.S. President Barack Obama said at an event in Milwaukee on Monday. "If I were busting my butt in the service industry and wanted an honest day's pay for an honest day's work, I'd join a union," he added, in an attempt to move Congress into action on the file.

The protests have been going on for about two years, but organizers have kept the campaign in the spotlight by switching their tactics every few months. In the past, supporters have showed up at a McDonald's shareholder meeting and held strikes. The idea of civil disobedience arose in July when 1,300 workers held a convention in Chicago.

Fast food minimum wage strike

Most fast-food workers in the U.S. take home about $15,000 per year at the current minimum wage rate. (Brendan McDermid/Reuters)

Kendall Fells, an organizing director for Fast Food Forward, has declined to say what exactly is in store for the protests, other than workers in a couple of dozen cities were trained to peacefully engage in civil disobedience ahead of the planned protests. But workers involved in the movement recently cited sit-ins as an example of strategies they could use to intensify their push for higher pay and unionization.

Past protests have targeted a couple of restaurants in each city for a limited time, in many cases posing little disruption to operations.

The National Restaurant Association said in a statement that the protests are an attempt by unions to "boost their dwindling membership."

Prospero Sanchez, who was at the McDonald's in New York, said the $11.50 an hour he earns making pizzas at a Domino's Pizza restaurant is not enough to support him, his wife and two kids. He started working at the same restaurant 14 years ago, when he made $5 an hour.

He has asked his bosses for more money. "They said no," Sanchez, 32, said.

The National Restaurant Association said in a statement that the protests are an attempt by unions to "boost their dwindling membership." The industry lobbying group said it hopes organizers will be respectful to customers and workers during the protests. 

With files from The Associated Press and Reuters