It’s the dam truth:

The fact doesn’t make intuitive sense if you think of mid-20th century America as an industrial powerhouse in a time before environmental regulation or solar and wind technology. But the era’s lower demand for electricity meant that hydroelectric power coming from the mega-projects of the 1930s, such as the Hoover Dam or the Tennessee Valley Authority, could do a lot of heavy lifting:

In 1950, nearly a third of all US power was hydroelectric. While more hydroelectric power is generated today, growing demand required non-renewable nuclear power and natural gas to fill the gap. Mega-projects like massive dams are falling out of favor—it’s much harder to raise billions and move entire communities today than it was in the Depression-era US, or even contemporary China.

There is some good news: Americans use less petroleum and coal for electricity than before, and wind power is playing a bigger role. But the overall mix is still dependent on the limited supply of fossil fuels we can dig out of the ground. With solar energy barely a rounding error here, you can see we have a long way to go before we meet Elon Musk’s promise of powering the entire US by covering a corner of Utah or Nevada in solar panels.

All this data comes from the US Energy Information Administration, by way of economist Tim Taylor, who noted a bunch of interesting social indicators released this year as part of president Barack Obama’s budget.

If you’re feeling like the US hasn’t come all that far in 64 years, at least we have this going for us: If you consider all energy consumption, not just electricity, there is some improvement. In 1950, 8.6% of energy consumed was produced from renewable sources; in 2014, it was 9.8%.