In the USA, out of every economic sector, transportation creates the most GHG emissions [EPA1], and the majority of that is from passenger vehicles [EPA2]. Significant portions of the industrial sector's emissions come from refining automotive fuel [EPA3]. US total GHG emissions are down around 20% from their peak in 2005, but almost all of that has come from the electrical power sector [CBO1][CBO2]. Vehicular pollution has dramatic direct health impact on top of GHG emissions [HSPH].

Transport emissions are the long pole in the tent for the US. Solutions to that will be the focal point of US climate strategy for the next decade. Barring the demolition of the majority of US housing to re-establish walkability, our two best solutions are EVs and public transit.

EVs cut lifecycle emissions by about 55-60%. [UCS][ANL][MIT][ICCT][BNEF][CB][MIT][IEA]

Public transit cuts lifecycle emissions by... about 55-60%. [IEA][AFDC][USDOT]

Neither is a magic bullet. Both get their asses kicked by bicyles (and to a lesser degree, microcars). Both get better with increased passengers per vehicle. Both can be fueled with renewable energy for additional reduction. Both can be manufactured with renewable energy for additional reduction. Both take surprisingly equivalent amounts of raw resources and energy. EVs need batteries that are carbon-intensive under current practices, but rail needs large quantities of steel which is equally carbon-intensive under current practices.

There are a ton of factors I can barely touch on here, so here's a rapid-fire overview. Public transit offers unique advantages from an urbanist perspective and the liveability of cities [ST], but that's objectively different from sustainability. The US has such low average ridership/occupancy that our busses have more emissions per passenger mile than our cars [AFDC1][AFDC2], and that was before the pandemic -- it's even worse now [NCBI]. Low ridership can be partly attributed to the incompatibility of American suburbs with public transit -- which could be a major roadblock because 2/3rds of Americans own detatched homes [FRED], representing $52t [PRN] in middle-class wealth that they will likely defend with voting power. Climate solutions will need to maneuver around this voting bloc. I personally think individual EVs and intercity rail are complementary technologies -- the more cheap (short-ranged) EVs are out there, the more people will lean on public transit for long trips. Heavy rail gets way better efficiency per vehicle mile than light rail or commuter rail and I have no clue why [APTA][ORNL], but I'm not as impressed by light rail as I expected to be. Since public transit and personal transport leverage different raw resources and face different challenges to adoption, we will achieve the most rapid decarbonization if we do both at the same time.

TL;DR

This is a huge, huge question, and anything short of a dissertation would fail to answer it objectively. My best answer is that the most effective solutions to climate change are diverse, engaging multiple technologies in parallel. EVs are a piece of the puzzle, but not a one-size-fits-all solution.