Great news for USA passport holders traveling to Argentina. As of today, March 24, 2016, The $160 Reciprocity Fee payment has been temporarily suspended according to Embassy of Argentina. There is no longer a fee to enter the country via air or land for American Citizens. (Canadians and Australians are still responsible for paying the fee before entering the country.)
The official statement from the immigration office:
The Argentine National Immigration Agency (Dirección Nacional de Migraciones) informed though Disposition 589/2016, that the “Reciprocity Fee has been suspended for American Citizens who travel to Argentina for 90 days or until the derogation of the regulation“ This measure starts on March 24th 2016.