USA to Europe from only $406 roundtrip

American Airlines have put many USA to Europe routes on sale over the summer.
For example, fly from Washington DC/Baltimore to Barcelona, Spain for only $406 roundtrip (see link below)
There are far too many routes to find example dates for. Simply use Google Flights to find a working date, then click the GO TO DEAL button below and proceed to book with Momondo.
https://www.google.com/flights
DEPART:
Washington DC/Baltimore/Chicago/Boston/Miami/Los Angeles/San Francisco, USA
ARRIVE:
Barcelona/Madrid/Ibiza/Palma de Mallorca/Valencia/Bilbao, Spain
Dublin/Shannon, Ireland
Rome, Italy
Paris/Nice, France
Vienna, Austria
London, UK
Munich/Frankfurt/Dusseldorf, Germany
Amsterdam, Netherlands
Porto, Portugal
Brussels, Belgium
Luxembourg
Geneva/Zurich, Switzerland
DATES:
Availability from August 2017 to May 2018 (excluding Christmas/New Year)
AIRLINES:
American Airlines
British Airways
Finnair
Iberia
Allow the Momondo search to complete, then book with the flight of your choice.
Example
http://m.momondo.com/results?cur=…&stops=any