The media in the U.S. is still not sure why President Obama is going to El Salvador (here is my post about how confused everyone was last month). The fact that the White House is not really explaining why doesn't help. From the New York Times' Caucus Blog:
Mr. Obama’s stop in El Salvador is as much about domestic politics as international affairs; one of the larger and fast-growing immigrant populations in the United States hails from this nation.
I don't buy it. Obama is not courting Salvadoran-American votes in the U.S. His trip will likely focus on gangs and drug trafficking, which are related to immigration but far more complicated than that.