Our recycling, composting and environmental correctness has been recognized yet again: San Francisco is the greenest city in the US and Canada, says an Economist Intelligence Unit study.

San Francisco scored 83.80 points out of a possible 100 in the environmental sustainability report, which covered 27 metropolises in the United States and Canada. The EIU’s US and Canada Green City Index examined statistics and qualitative factors in nine categories ranging from public transportation to environmental governance.

San Francisco was one of the top five cities in six categories: energy use; energy efficient building regulations and buildings; green transportation; water conservation; air quality; and waste reduction/recycling. We didn’t do as well when it came to carbon dioxide emissions, land use/green space and environmental governance. But still, we and second-place Vancouver, B.C., were the only ones to rank among the top 10 cities in all nine categories.

We are the uncontested champs of waste management, with the highest recycling rate of all of the cities. The report highlights the 2009 garbage laws that made us the first city in the US to require residents and businesses to compost and recycle using the black, green and blue bin system.

As of 2009, San Francisco recycled 72 percent of its waste, which was already more than any of the other cities in the study. Our 2010 goal was 75 percent. And at the time, more than a third of our trash was actually compostable.

Within a year of the composting and recycling mandates taking effect, our recycling rate grew to 77 percent, and we were composting 600 tons per day, up from 400 tons previously.

The average recycling rate of the 27 cities is only 26 percent.

After San Francisco and Vancouver, New York, Seattle and Denver were the other five greenest cities. Least green: Cleveland, St. Louis and Detroit, each of which scored less than 40 points.

Of all of the cities, San Francisco was the second most densely populated (after New York) and had the second-highest GDP per capita, $60,300 (after D.C.’s $60,500).

One debatable finding by the EIU was San Francisco’s “exceptional public transport infrastructure.” Apparently the researchers did not poll any MUNI riders.