The wind industry crossed an important threshold in the United States last year, exceeding the generating capacity of hydroelectric power for the first time, according to the main industry trade group, the American Wind Energy Association.

The nation’s fleet of dams has long stood as the top renewable energy source, but there has been little market interest in building more big hydroelectric generating stations. In the meantime, wind has rapidly expanded — more than tripling in capacity since 2008 — with many more installations on the way.

An Important Asterisk

The comparison here is limited, measuring the maximum amount of power that generating stations are rated to produce — a threshold few, if any, ever meet. According to the Energy Information Administration, conventional hydroelectric generating capacity stood at 78,956 megawatts in 2015, while wind, the industry group says, reached 82,183 megawatts last year, about enough to run 24 million average American homes. (The hydroelectric figure does not include pumped storage, in which water pumped to an elevated reservoir can be released through a turbine to generate electricity when needed.)

But hydroelectric power could still lead in terms of actual production: According to the Energy Information Administration’s most recent annual electric power report, hydroelectric edged out wind in terms of power sent to the grid by roughly 30 percent in 2015, though both forms trailed fossil fuels and nuclear power by wide margins.