Fig. 3.

Time series of US per-capita on-road CO₂ emissions by county, using a Census 2000 Metropolitan Statistical Area (MSA) classification. Per capita emissions increased from 1980, both in urban and nonurban counties, with brief declines during the 1981–1982, 1990–1991, and 2007–2009 economic recessions. Since 2009 per capita emissions in non-MSA (rural) and outlying MSA (suburban) counties have grown rapidly, whereas central MSA (urban) per capita emissions have continued to decrease.