America’s electricity mix has undergone profound changes over the last decade, with natural gas and renewables rising and coal declining.

The big picture: The energy revolution has occurred differently across the U.S., so let’s tell these stories through four states whose electricity mixes are notable for one reason or another.

1. Massachusetts: In light of last week's tragic natural-gas explosions, it's worth noting that the state's reliance on the fuel has increased in the last several years, from just above 50% to nearly 80%.

2. Iowa: This political battleground is known most for ethanol when it comes to energy. But its wind industry is quickly becoming a force to reckon with as its share has increased sharply, at coal’s expense.

3. Delaware: This is ground zero for America’s shift from coal to natural gas. Here’s a staggering stat: Delaware generated 87% of its electricity from natural gas in 2017, almost five times more than its share a decade earlier. Its dependence on coal power fell to 4.7%, down from 70% a decade ago, according to the U.S. Energy Information Administration.

4. California: The Golden State has recently adopted aggressive clean-energy goals in the last month, mandating that 100% of its electricity come from carbon-free sources by 2045, including a renewable-specific target of 60% by 2030. Often a bellwether for other progressive state policies, California’s shift away from natural gas is markedly different than even other progressive states (like Delaware).

Go deeper: America’s renewable electricity ticks up