NEW YORK (CNNMoney) -- Fast food workers in 50 cities across the U.S. are walking off the job Thursday as they protest for higher wages.

Organizers say it will be the largest strike to hit the $200 billion fast-food industry.

Workers from fast food giants McDonald's, Burger King Wendy's and Yum Brands-owned KFC are calling on their employers to pay them a minimum of $15 an hour and allow them to form unions without retaliation.

Currently, the median pay for the fast food workers across the country is just over $9 an hour, or about $18,500 a year. That's roughly $4,500 lower than Census Bureau's poverty income threshold level of $23,000 for a family of four.

Strikes are planned in Boston, Chicago, Denver, Houston, Los Angeles, Memphis, New York and dozens of other cities.

The campaign, organized by a coalition of labor, community and clergy groups called Fast Food Forward, has been building momentum since last November, when the protests first hit the national spotlight.

Organizers say retail workers from stores such as Macy's, Sears, Walgreens and L Brands' Victoria's Secret will also go on strike Thursday in some cities.

Latoya Jemes, who's been working at a Memphis McDonald's for the past year, said she plans to join the protests.

She makes $7.45 an hour, and has to work overnights because she can't afford childcare during the day. Her mother watches her children during the night.

"I'm a single parent of three, and I'm living check to check," said Jemes, 24. "I only have enough to pay my rent, and I might be able to squeeze out the things that my kids need, but I'm not making enough."

The protests have caught the attention of the White House. Earlier this summer, the "low-wage worker" protests were mentioned in a blog post written by National Economic Council director Gene Sperling and chairman of the Council of Economic Advisers Alan Kruege. They said that raising the minimum wage was part of President Obama's economic vision.

--CNNMoney's Emily Jane Fox contributed to this report.