Mackenzie McDonald beat Lukas Klein 6-4, 6-3 in the day's opening singles before Brandon Nakashima beat Jozef Kovalik also in straight sets to give the Americans an unassailable 2-0 lead.
It was the second group win for Bob Bryan's team who are missing a host of top singles players including US Open runner-up Taylor Fritz. They also beat Chile 3-0.
Victory for the US also meant Germany qualified for the final eight which will be held in Malaga in November.
Germany and the US play in the final group game on Saturday with top spot at stake.
Spain also booked their final eight spot as they beat France in Group B in Valencia following their hard-fought victory against the Czech Republic on Wednesday.
Roberto Bautista Agut came from a set down to beat Arthur Fils 2-6 7-5 6-3 before world number three Carlos Alcaraz dismantled Ugo Humbert 6-3 6-3 with one match still to play.
"I was pleased with the level I played from the beginning till the last ball. I was really focused," Alcaraz said.
"It was a high level of tennis. I was really, really intense. Probably one of the best matches I've played this year."
Nervy ending for Italy
Reigning champions Italy earned their second Group A win, needing the doubles to settle their clash with Belgium in Bologna.
Matteo Berrettini fought back against Alexander Blockx to beat the 19-year-old, making his Davis Cup debut, 3-6 6-2 7-5.
Zizou Bergs then levelled the tie for Belgium with a 6-3 6-7(5) 6-0 win over Flavio Cobolli before Simone Bolelli and Andrea Vavassori beat the duo Sander Gille and Joran Vliegen in straight sets.
Belgium face Brazil and Italy play the Netherlands in their final ties over the weekend.
In Group D, played in Manchester, Argentina maintained their over century-long winning streak against Britain in the competition with a 2-1 victory.
Tomas Etcheverry beat Daniel Evans 6-2 7-5 and Francisco Cerundolo went on to win 7-6(4) 7-5 against US Open semi-finalist Jack Draper for Argentina to bounce back from their 2-1 defeat by Canada.
Evans then teamed up with Neal Skupski for a 6-3 7-5 win over Maximo Gonzalez and Andres Molteni in the doubles.
Argentina's win means that all four Group D teams go into the weekend holding a chance to reach the final eight, with Finland taking on Argentina on Saturday and Canada facing Britain on Sunday.
