The US is the main overseas investment market and the main single country export market for UK businesses.
The US market is vast - differing by state and region - and forms part of a free trade area with Mexico and Canada.
The business culture and most other practical aspects of living and working in the US are significantly different. It could be easier and more cost-effective to work with - or for - UK businesses already trading with the US, those with a presence there, or US businesses established in the UK.
There has been a recent development in US national and local policy to prioritise climate change, which has led to new business opportunities in environmental products and systems.
The UK has its own bilateral trade relations with the US. It also works through the European Union (EU). In 2007, the EU and US set up the TransAtlantic Economic Council (TEC), with forums for business, consumers and legislators to promote open trade.
HM Revenue & Customs (HMRC) provides practical advice on importing and exporting.