Workers demanding the Los Angeles City Council to vote to raise the minimum wage Tuesday, May 19, 2015, in Los Angeles.

As Los Angeles moves to become the largest city to raise the minimum wage to $15 an hour from $9 an hour over the next five years, a key question is which other large cities might follow suit and hike pay.

Los Angeles joins other cities including Seattle, San Francisco and Chicago that have moved independently to raise wages beyond the current, federal minimum wage of $7.25 an hour.