Minimum wages by state. (Urban Institute)

At least 10 states and D.C. passed minimum wage increases this year, with four more set to join them — if voters approve the hikes this fall.

The measure before voters in Alaska would set the minimum wage the highest, to $9.75 an hour by 2016. A Nebraska measure would set it to $9 per hour by then, too. In South Dakota, voters will consider raising the minimum wage to $8.5 per hour by next year, while Arkansans will consider hiking it to the same level, but by 2017. (Illinois voters will give their opinion on a hike to $10 in 2015, though that measure is not binding.)

The federal minimum is $7.25, with 23 states and D.C. having set their own floors above that level, while nine states default to the federal minimum because either they lack one of their own or theirs is set below that level, according to the Urban Institute, which created the map above for its State Economic Monitor report. Minimum wages are at or above $9 an hour in Washington, Oregon and California. Fourteen states index their minimum wage to inflation — that is, it rises as costs rise.

Even without voter approval or further legislative action, the minimum wage is set to change in at least a dozen states and D.C. over the next few years. Four states will see their minimum wages rise to at least $9 an hour early next year, joining Washington, Oregon and California. By early 2016, two states — Massachusetts and California — will breach a $10-minimum-wage mark. By early 2017, Massachusetts will have an $11 minimum wage.

Here’s a look at the scheduled increases:

* Changes in New York and West Virginia go into effect on Dec. 31. All others go into effect on the first of the given month.