Following announcements last week of closures in Maryland and Pennsylvania, the group said the nation had lost 158 of its fleet of 523 facilities.
The Sierra Club said the closures were helping it meet its goal of moving the US “beyond coal” by 2030.
“As the country invests in more clean energy, polluting coal plants are now obsolete,” Sierra Club contributor, Bloomberg Philanthropies founder and New York City Mayor Michael Bloomberg said.
“Every American will benefit from the retirement of these 158 coal plants with cleaner air, lower healthcare costs and less climate-disrupting pollution.
“Make no mistake – coal is going away for good.”
The environmental group said the retirements would equate to life savings in the form of preventing 4400 premature deaths, 6800 heart attacks and 72,000 asthma attacks annually, along with a $2 billion reduction in health costs.
Beyond Coal campaign director Bruce Nilles said the nation is at a “transformative moment” in history.
“The end of coal is coming and millions of Americans are already benefiting from cleaner, affordable, more modern sources of energy like wind and solar,” he proclaimed.