How does the EU benefit the U.S?

I'm doing a project on reasons why Turkey should be in the EU and I need five specific countries and how Turkey's membership could benefit them.

It appears that advanced Asian financial centres like Hong Kong and Singapore benefit from their Foreign Domestic Helper (FDH), or 'Maid', visa programs, by allowing both parents to work full-time without the need to pay high childcare costs.   Would...

Lets say a country like Turkey, it wants to be a member, but cannot. How will it benefit to the EU as well?

Also, how has France contributed to the EU?

When Sweden joined the EU, what benefits did they have?

I am aware of the benefits of EU membership to the UK but in what way does the EU as a whole or other EU countries benefit from the UK's involvment in the EU?

Since a question has been posed on the UK leaving the EU and setting up a trade relationship with the EU similar to Norway's. What would be the effect of carrying the concept a bit further and considering the ramifications of the UK leaving the EU and...

Over the last ten years, British trade with the world outside of the EU has grown significantly faster than British trade with the EU. Source: ...show more

I appreciate some will say never, that is not an answer. The UK did benefit but when do you feel the cost of membership out weighed the benefit?