The protests demanding pay increases to $15 an hour kicked off at dawn outside a McDonald's Corp (>> McDonald's Corporation) restaurant in New York with several hundred demonstrators.

Marching behind a banner reading "Raise wages, Raise the city," protesters carried placards with "Fight for $15 on 4/15."

In Chicago, hundreds of protesters rallied at the University of Illinois, their ranks swelled by healthcare and college workers.

"I have no benefits, I have no stability from semester to semester in any way being able to calculate out if and where I'll have a job," said Alyson Warren, 34, an adjunct writing professor at both Columbia College Chicago and Loyola University Chicago. She said Loyola pays $4,000 to $4,500 per 15-week course, and her group seeks $15,000 per course.

Roughly two dozen people were arrested for civil disobedience after blocking a street near Seattle University in protest, including some students, according to labor group Working Washington.

Plans called for rallies to be held in 230 cities across the United States.

Jumal Tarver, 36, said he cooks and cleans at a franchised McDonald's in Manhattan but cannot make ends meet on his pay of $8.75 per hour.

He said he must rely on public assistance on top of his wages.

"It's hard for me to provide for my daughters with $8.75," he said.

Organizers said they chose to mobilize on April 15, the U.S. deadline for filing federal income tax returns, to highlight their complaint that many workers must rely on public assistance.

The campaign for a living wage has been building on low-paid workers' position that the U.S. federal minimum wage of $7.25 an hour is not enough to lift them from poverty.

Fast-food and retail chains are starting to respond, but their wage increases are generally less than organizers demand.

Wal-Mart Stores Inc (>> Wal-Mart Stores, Inc.) this year said it would raise its minimum pay to $9 an hour in April, and $10 in 2016. Target Corp (>> Target Corporation) and T.J. Maxx (>> TJX Companies Inc) said they would increase pay to $9 an hour.

McDonald's has said it would raise hourly pay at company-owned stores to $9 but this would not necessarily apply to the more than 90 percent of its 14,000 U.S. locations operated by franchisees.

Wages are expected to emerge as an issue in the 2016 presidential election campaign.

Democratic candidate Hillary Clinton this week said it was unfair that many families face financial hardship "when the average CEO makes about 300 times what the average worker makes."

(Additional reporting by Nathan Layne in Chicago; Writing by Ellen Wulfhorst and Barbara Goldberg; Editing by Doina Chiacu and Mohammad Zargham)

By Sebastien Malo