Use a modified version of what the rest of the world has been doing for decades. It's going to require people to make investments in public transportation in the form of a redistribution in the way we spend tax dollars.
I just want a bus that comes by my house so often I don't need a schedule.
Making out towns and cities walking is also a good place to start.
Creating citywide networks of protected bike lanes can reduce car traffic.
Embracing a mandatory work from home program that takes cars off the road on specific days will absolutely reduce traffic.
Slowly you work down to why people need to own cars in the first place... and that's because there is no easy and affordable way for a majority of Americans to travel between cities.
High speed rail. Reinvestment in AMTRAK. Dedicated high capacity lanes on existing interstate infrastructure.
