Sheffield can attract more global firms like Boeing as its reputation grows, the US ambassador to the UK said.
Woody Johnson said the aerospace giant's first factory in Europe was testament to just how good the city is.
He was one of a host of global VIPs at the launch of the £40m facility near Catcliffe. He also had a tour of the University of Sheffield's Nuclear Advanced Manufacturing Research Centre.
He said: "That Boeing is here is a testament to how good Sheffield is. It is one of the world's great companies. As this city grows and prospers you could attract more big businesses like it.
"You've got a great workforce and apprenticeships programme. And looking at what you are doing in R&D alone, that is going to blow their minds. I was extremely impressed by the Nuclear AMRC, my knowledge was doubling every few minutes."
He added: "Sheffield’s got great businesses and it looks like it's on the up and up."
Mr Johnson said President Donald Trump was "very enthusiastic" about an "amazing bilateral trade agreement that would be huge."
"That's something he and I want to accomplish, if you are free to make a deal like that."
UK-US trade is worth $230bn, he said. The UK cannot strike a US trade deal until it leaves the EU on March 29 next year. Embassy staff said the quickest US trade deal was with Australia and it took a year.
Mr Johnson added: "It's going to be good for Britain ultimately. If you have some pain go through it - and let's go."
The US imposed trade tariffs on steel and aluminium earlier this year.
Mr Johnson said he believed the US was now looking at its tariffs "country by country."
He added: "We have a great relationship. There's no country we have a closer relationship to than the UK and the president knows that. A robust trade agreement with the US would be extremely advantageous to this country.
"It's great to be here in Sheffield, it brings a lot to the table such as technology and motivation for other parts of the UK. I think it can be a leader for the rest of the country."
Meanwhile, Mr Johnson said Lord Mayor Magid Magid’s ‘ban’ on President Donald Trump from Sheffield was "gratuitous.”
He added: “What are you hoping to accomplish? I don't think it would encourage business from the US. And I wouldn't accept he has reason to do that for one second."