Wimbledon champion Murray broke his big-serving opponent five times on the red clay surface to give Britain an unassailable 3-1 lead and the final match of the rubber, between James Ward and American Donald Young, was scrapped.
Roared on by the minority of British fans in the stands at Petco Park, world number six Murray sealed victory over the 49th-ranked Querrey in just under three hours, improving his Davis Cup record to 18-1 in singles and 21-6 overall.
Murray yelled out in delight when the match ended as a backhand service return from Querrey sailed wide, giving Britain their first success in a World Group tie since beating Spain 4-1 in 1986.
"It's obviously nice," Murray, 26, said in a courtside interview after winning both his singles matches in San Diego. "You want to try and contribute as much as possible in these weeks.
"James had a great win against Sam on the first day to put us in that position and it was up to me to try and close it out today, and thankfully I managed to do it," he said.
Ward, the world number 175, had given Britain a commanding 2-0 advantage over the Americans on day one with a shock win over Querrey after clawing his way back from two sets to one down and trailing 2-4 in the fourth.


Latest News from Sports News Desk