Last week, the U.S. Green Building Council (USGBC) released its ranking for the Top 10 LEED-certified states—those states that best exemplify green, sustainable design.

Highlighting those regions around the country that are leading the way in sustainable transformation, the list focuses on states that encourage the construction of LEED-certified spaces that save energy, reduce carbon emissions, and contribute to an overall healthier environment.

Using U.S. Census Data from 2010 through 2013, the list’s top position is held by Illinois, certifying 171 projects, representing 229 sq. ft. of LEED-certified space per resident.

Massachusetts made the fourth spot on the list, with 101 LEED-certified projects, including the LEED-platinum certified Massachusetts Green High Performance Computing Center in Holyoke—the first university research computing center to ever achieve Platinum status.

Altogether, more than 20,000 projects representing 2.9 billion sq. ft. have been LEED-certified worldwide—and the green industry’s growing.

According to McGraw Hill Construction, projects in the sustainable design industry could be worth up to $248 billion in the U.S. alone as early as 2016.

For an infographic outlining the results of the list, click here.