You’ve been watching too many Star Trek shows. No matter what the USA would have done or could have done — there would be no travel between solar systems - today, as we speak.
In the late 50s - early 60’s, there were plans to build a super sized 40 million ton Orion interstellar ship with a crew of thousands.
The 40 ton interplanetary Orion would have had a crew of several hundred. (Cargo weight 1300 tons, acceleration 12 meter/sec ). Orion's motto was Mars by 1965, Saturn by 1970.
Wernher von Braun supported the original design. AC Clarke originally had an Orion ship for his “2001 Space Odyssey” movie.
Orion was killed in 63. And the Apollo Program began.
And keep you eyes on China - they would have no problem launching a similar ship.