Ever since lowcost airlines started out, there’s been a huge fare battle for the transatlantic routes. A new highlight: a current deal allows you to travel from most German airports to lots of destinations in the USA, for less than 300€! All flights are done by Star Alliance members, so you’ll fly with Lufthansa or its partner airlines (Swiss, Austrian, United, Brussels, Air Canada). These are all roundtrip fares of course, only the luggage would be extra if needed!
Here are a few examples:
Frankfurt – New York (10.9. – 17.9.): 282€
Berlin – Boston (6.11. – 13.11.): 297€
Munich – San Francisco (19.10. – 27.10.): 322€
There is a ton of availability throughout the whole year, with the best deals in fall and winter. Try to avoid the main season in summer, as prices are high then.
Just use Google Flights to search for your preferred flight: