There is no doubt that a UK withdrawal from the European Union following the June referendum will have profound implications for Britain but it is in Northern Ireland where the effects will not only be far-reaching but immediately visible.
According to a Cabinet Office paper on the impact of a vote to leave the EU, we can expect to see a return of customs posts on the only land border between the UK and an EU member state.
The assessment warned that breaking the link with Brussels would confront Northern Ireland with difficult issues over its relationship with the Republic, saying it ``would be necessary to impose customs checks on the movement of goods across the border.''
Meanwhile, there is also the question of the movement of people which the paper says ``could have an impact on cross-border cooperation and trade.''
These are clearly major issues for both north and south.
Many people will remember the presence of customs posts and the lengthy queues faced by those travelling across the border.
It seems unthinkable now that someone travelling between Dundalk and Newry or Derry and Bridgend might have to negotiate a checkpoint of some kind.
For a significant number of people who criss-cross the border every day going to work or carrying on their business, this would be a major inconvenience.
For those transporting goods, there is the prospect of long delays as they wait for a customs check on a lorry or container while shops and businesses waiting for supplies could see their trade disrupted.
Limiting the free movement of people and goods would have enormous repercussions for border towns and cities and could prove deeply damaging to the wider economy. Any customs post would also give rise to security issues.
These are all matters that people need to think carefully about ahead of the June 23 referendum.
No one is claiming the EU is perfect but leaving would plunge us into a more uncertain economic future.
