MLS has long been rumored to be exploring the possibility of utilizing instant replay. While goal-line technology isn't quite as expansive as the project MLS has been rumored to be exploring, we will at least get a glimpse of that during Copa America Centenario.
Hawk-Eye Goal Line Technology is the same system that was used in the 2014 World Cup and 2015 Women's World Cup as well as in the English Premier League, Bundesliga, Serie A and UEFA competitions. The system utilizes seven cameras on each goal that track the ball and notify the referee within 1 second of the ball crossing the line.