What effects? ("Impact" implies hitting!)
Multiple effects ... what have you thought of so far?
what impact does current immigration have on the development of the united states?
2 answers
Read lots, and take good notes.
http://www.google.com/search?q=effects+of+immigration+on+the+USA&oq=effects+of+immigration+on+the+USA&aqs=chrome..69i57.6572j0j7&sourceid=chrome&es_sm=122&ie=UTF-8
http://www.google.com/search?q=effects+of+immigration+on+the+USA&oq=effects+of+immigration+on+the+USA&aqs=chrome..69i57.6572j0j7&sourceid=chrome&es_sm=122&ie=UTF-8