If you are a United States citizen or a resident alien, you are taxed on your worldwide income in the U.S.
For a 1031 exchange, you should contact a qualified intermediary and note that a "partial exchange" would merely entail the seller receiving boot.
See https://www.google.com/search?q=qualified+intermediary+1031&ei=CxVbYd_VF4qUwbkPotyjwAw&ved=0ahUKEwif...
