Climate Change: State and Local Efforts to Reduce Greenhouse Gas Emissions from Vehicles

Greenhouse gas emissions contribute to climate change, which numerous studies have shown poses environmental and economic risks. The transportation sector is the largest source of greenhouse gas emissions in the U.S., with transportation activities accounting for 29 percent of total U.S. emissions in 2021, according to the Environmental Protection Agency. The vast majority of these emissions occur on the nation’s 4-million-mile network of roads, most of which are owned and operated by state and local governments. The Explanatory Statement on the Consolidated Appropriations Act, 2022 included a provision for the Government Accountability Office (GAO) to examine the extent to which states and metropolitan planning organizations (MPOs) collect performance information on transportation-related greenhouse gas emissions, among other things. This report describes activities selected state departments of transportation (DOTs) and MPOs have taken related to estimating, analyzing the effects of transportation investments on, and using reduction targets for on-road greenhouse gas emissions. GAO reviewed federal statutes, regulations, executive orders, and other information on greenhouse gas emissions. GAO also interviewed federal officials as well as officials from a non-generalizable selection of 10 state DOTs and 10 MPOs. GAO selected states that varied in greenhouse gas emission policies, population, and geographic area, and generally selected the largest MPO from each of these states.


  • English

Media Info

  • Media Type: Digital/other
  • Features: Appendices; Figures; Photos; References; Tables;
  • Pagination: 32p

Subject/Index Terms

Filing Info

  • Accession Number: 01889957
  • Record Type: Publication
  • Report/Paper Numbers: GAO-23-106022
  • Files: TRIS
  • Created Date: Aug 14 2023 8:52AM