zz:
Re: “Is the US auto industry going to flourish now that steel will cost 25% more and aluminum 10% more?”
It's bigger than that.
President Trump has been pushing for infastructure improvements throughout the nation. That includes the border wall, highways, bridges, prisons and more. It's Yuuuge! When that legislation passes, U.S. steel and aluminum companies bidding for the contracts will be competitive with foreign companies (many of which are sponsored by governments) for the first time in decades. That means jobs, a rising stock market and happier voters.
You'll notice that President Trump is now stumping in Pennsylvania. Guess why? His popularity will soar in Pennsylvania, Michigan, Virginia, West Virginia, and in every other state where commodity production plays a role in the economy. Then, as the infastructure improvements become apparent to the population, his popularity will rise amongst everyone else. This move all but cements his 2020 victory.
I've been calling for tariffs for twenty years, btw. Right there, you know it's a brilliant move.