Nearly half of U.S. states are set to raise their minimum wage at the outset of 2025, boosting pay for millions of workers stretching from California to Maine.

In all, 21 states will raise their wage floors on Jan. 1 in keeping with inflation-adjusted increases or as part of scheduled hikes that take effect at the beginning of each calendar year.

The pay increases will affect about 9.2 million workers, who will gain a combined $5.7 billion over the course of 2025, according to the left-leaning Economic Policy Institute, or EPI.

After the wave of wage hikes, Washington will become the state with the highest minimum wage, offering workers $16.66 per hour. Workers in California and New York will enjoy the second-highest wage floor, as both states implement a minimum hourly wage of $16.50.

Pay increases set to take hold in the new year will bring the wage floor to $15 an hour or higher in Washington, D.C., as well as 10 states, among them Delaware, Illinois and Rhode Island. Those areas play host to one of every three U.S. workers, EPI found.

Overall, the states set to raise their minimum wage on Wednesday include: Alaska, Arizona, California, Colorado, Connecticut, Delaware, Illinois, Maine, Michigan, Minnesota, Missouri, Montana, Nebraska, New Jersey, New York, Ohio, Rhode Island, South Dakota, Vermont, Virginia and Washington.

The nation’s highest wage floors will take effect in some of the nearly 50 cities and other localities that will impose minimum pay hikes.

Twenty-nine cities in California will see pay hikes, including a $17-an-hour wage floor that will take effect in Oakland. Seven localities in Washington will increase their minimum wage, among them the country’s highest wage floor: $21.10 an hour in Tukwila.

The latest round of pay increases, however, will not affect more than a dozen states concentrated in the South that lack a minimum wage or offer a minimum wage that does not exceed the federal minimum of $7.25 per hour.

The last federal minimum wage hike took place in 2009, when Congress raised the pay floor to its current level. When adjusted for inflation, the federal minimum wage stands at its lowest level since February 1956, nearly 70 years ago, EPI found.