The logic is quite simple. Many economists have concluded that if the UK leaves, it will be economically worse off. Oxford Economics found that in eight of out nine possible scenarios the UK economy would be badly affected.
In all but one of those scenarios the Northern Ireland economy would be hit worse, because of its cross border trade with the South.
Bearing in mind that people living in border counties rely on the performance of the economy on both sides of the divide, they in turn could be especially badly hit.
So it is all the more puzzling that the First Minister and DUP leader Arlene Foster has chosen to back an exit. It appears to be more about British sovereignty issues than economic ones.
But large swathes of the business community in the North are backing the stay campaign. Farmers also could have a lot to lose from an exit.
The Ulster Farmers' Union (UFU) is backing a stay vote although it acknowledges the issue is causing actual splits within farming families.
Local farmers and other landowners in the North received £349m (€450m) in EU Common Agricultural Policy (CAP) payments in 2013-2014. Many farmers are worried that single farm payments which might account for half their income, would disappear.
The 'leave' camp argues that the UK contributes over £9bn to the EU each year and this money would be available to farmers all over the UK. But the big uncertainty is how much of it would go to farming.
Farmers don't like risk and some see that uncertainty as a genuine risk they don't want to take.
The possible impact on rural communities in border regions isn't just about goods and services. It is about movement of people. Even if an exited UK negotiates to continue with a free movement area between Ireland and the UK, it still may need customs checkpoints.
These in turn could dramatically slow down people's commute times and make it less worthwhile to cross border commute or travel for business.
Increasingly rural economies are relying on those living there to actually commute to work somewhere else.
Around half of all working people living in rural Ireland commute to large towns or cities. If that town happens to be near the border, there would knock-on effects.
I live in Inishowen in North Donegal. It has sea on three sides and another state (namely Derry City) to its south.
There are also just a handful of roads to the south west that link the peninsula directly with the rest of Donegal.
If I want to travel to Dublin, I must go through Northern Ireland and make two border crossings each way or go around the long way and add close to 80 miles to my round trip journey. Border counties are full of people in similar situations.
Those living along the border, whether they are farmers, tradespeople, businesspeople or commuters could have a lot to lose when the referendum votes are counted next month. Unfortunately, there is really nothing they can do about it.
Richard Curran is a columnist with the Irish Independent and presents RTE's Dragons' Den TV series