Tyler Adams wore the armband for the U.S., becoming the youngest player in the modern era to do so, while both Christian Pulisic and Zack Steffen were not with the team as they both recovered from setbacks.
The teams traded headed opportunities in the opening 15 minutes with Gold Cup hero Miles Robinson of the U.S. and El Salvador's Ronald Rodriguez both sending efforts from set pieces narrowly over the crossbar.
The U.S. grew into the tail end of the second half with Josh Sargent getting more involved in the Americans' attack, but neither team scored and the teams went to the break locked in a goalless draw.
Goals continued to be impossible to come by for either side, and U.S. manager Gregg Berhalter made a trio of substitutes just past the hour mark, bringing on Jordan Siebatcheu, Antonee Robinson and Kellyn Acosta to try to jumpstart his team's attack.
Weston McKennie flashed a header wide and Acosta's nodded effort came back off the bar and was smothered by El Salvador keeper Mario Gonzalez as the match approached the 80-minute mark.
Neither team could find a winner and had to settle for a point, with the U.S. next in action in Nashville against Canada on Sunday.
"All these games are going to be hard fought," Berhalter told reporters after the draw. "Anytime you go away from home, it's going to be a difficult game. Any intentions of us coming here and winning 3-0, it's going to be really challenging. Look at the other scores around CONCACAF, all the ties, Mexico winning in the 90th minute at home.
"They're dogfights and as much as I'd want to win this game, and we did want to win this game, I think that the attitude and the play was trying to win the game for the whole 90 minutes," Berhalter said.
"We'll take the point and we'll move on. We know the next game is a home game against Canada followed by Honduras and we want to pick up points in those games."
The U.S., trying to rebound from its failure to qualify for the 2018 World Cup, is ranked 10th, its highest since 2006, after winning the CONCACAF Nations League and Gold Cup, and El Salvador is 64th. Los Cuscatlecos have reached just two World Cups, in 1970 and 1982, and the U.S. has 18 wins, six draws and one loss in the matchup, which includes an 18-game unbeaten streak (15 victories). The U.S. had won the most recent meeting 6-0 in an exhibition in December.
Three of the eight nations in the regional Octagonal finals qualify for next year's World Cup in Qatar and fourth place advances to a playoff.