You need to add Germany, France and rest of EU together really then there bigger than USA.
Based on this data from 2017 for goods and services:
https://en.wikipedia.org/wiki/List_of_the_largest_trading_partners_of_United_Kingdom
UK imports more from the EU than it exports to the EU.
UK imports less from the US than it exports to the US.
If Brexit negotiations had been approached
commercially by establishing the desired outcomes for each side prior to the negotiating terms, we'd have got somewhere. I believe this is the approach that David Davis started with. Instead, the UK team allowed the EU to turn this into a political negotiation accepting that the negotiating order and method of withdrawal had to be agreed prior to negotiating any future trading terms (btw, this is what makes talk of any 'exit deal' ridiculous. There's no trade deal, just an agreement about a divorce settlement). Overall, a weak and b*ll*cks approach.
In business, you establish where you want to be, aim for some common ground, then work out a way to get there. The EU doesn't want the UK (or anyone) to leave, otherwise 10 gazillion unelected people in Brussels lose their jobs. The first leaver needs to be dissuaded/punished so that no one else is tempted to leave. Hmmm. Sounds good. Democratic. To do this, they set their stall out as 'we must agree the basis of leaving before we even look at doing business in the future'.
If this was a commercial negotiation with someone
that sells more to me than I buy from them my response would be 'come back when you're actually ready to do business'.
The facts (that the 'remoaners' like to gloss over or partially present) are the
the EU sells more to the UK than the UK sells to the EU. It is in the EU's commercial best interest to avoid trade friction. The UK should grow a pair and just leave. A deal will be struck.