One goal was enough for the USA to secure three important World Cup qualifying points as they moved closer to a place at Qatar 2022.
Christian Pulisic started in attack for the Stars and Stripes, the 23-year-old also wearing the armband for the first 65 minutes before he was replaced with the deadlock finally broken.
In sub-zero temperatures in Ohio, Gregg Berhalter's side had to be patient in breaking down a stubborn El Salvador side, with FC Dallas forward Jesus Ferreira spurning two decent early opportunities to open the scoring.
Despite registering eight attempts on goal in the first half, none of the USA's efforts were on target and so a second-half improvement was needed against a side struggling near the bottom of CONCACAF qualifying.
Fulham full-back Antonee Robinson provided the decisive moment, rifling a finish into the bottom corner after latching onto a loose ball at the back post seven minutes after the restart, and that proved to be the only goal of a cagey contest. It continued a familiar theme for America in qualifying, with 11 of their 13 goals having been scored after half-time.
Pulisic was replaced by RB Salzburg's Brendan Aaronson just after the hour mark, with the USA facing two more qualifiers in the next six days, away at leaders Canada and at home to Honduras.
The top three in this eight-team group automatically advance to the World Cup finals, with the States currently second. Just two points separate the top three, which includes Mexico in third. Canada and the USA meet in Ontario on Sunday.