States in blue require highway projects to meet state environmental review rules (as of 2014).
How state and federal project environmental reviews compare on key requirements

Despite concerns that required environmental reviews of highway projects by federal authorities and a number of states are slowing job progress, a new report by the U.S. Government Accountability Office contends there is minimal duplication between project reviews required under the National Environmental Policy Act and similar rules mandated in 18 states.

According to GAO, 17 of those states allow for partial or full adoption of Federal Highway Administration environmental review analyses or documentation to meet state rules on federally funded projects.

Officials in four states noted instances of potential federal-state duplication, stemming from either supplemental state requirements, lack of alignment between required documents in the differing reviews, or because another permitting agency such as the Army Corps of Engineers or the U.S Coast Guard chooses to conduct its own review.

Officials in three states said that, in practice, they match FHWA's public involvement requirements for state-only reviews to "meet public expectations, even if state law requires less," according to the report.

State officials in Hawaii, Washington, Maryland, North Carolina and Wisconsin said they vet projects under FHWA environmental review rules, even when there is no federal funding.

Washington DOT officials told GAO the federal rules were preferred "because they felt more certain about how ... the NEPA requirements would be interpreted by courts" if there were a legal challenge to a project environmental review.

DOT officials in California prefer the federal environmental rules, citing the "positive working relationship" with FHWA and the potentially more burdensome requirements that could be triggered by the Endangered Species Act, says GAO.

However, DOTs canvassed in Massachusetts, Minnesota and North Carolina said they rejected federal-aid funding on some projects to avoid the federal reviews, although GAO's report contends their highway projects would still be subject to compliance under the federal Clean Water Act.