Do you think vetting should have been used during the 19th century on the Irish/Italians?

British values not just English. The USA was never an English colony, it was British.

Not sure why you think potato blight made the 'English' responsible.it is a disease caused by a fungus-like organism that spreads rapidly in the foliage and tubers or fruit of potatoes and tomatoes in wet weather, causing collapse and decay, the Irish only grew one variety, much the same as they did in Scotland, both countries suffered famine and food supplies were sent to both Scotland and Ireland which at that time Ireland was British as well, in fact blight hit English and Welsh farming too however less problem as they planted lots of varieties so it didn't wipe out whole crops, just some crops ...in as far as Irish leaving to migrate to the USA huge numbers passages were paid for by British Government money and British charities and as many Irish migrated to mainland Britian too.

The USA took in many many terrorist/activists/crooks escaping from both Ireland and Italy as they did later on with escaping nazi Germans although they liked to reinvent themselves and hide, where as the Irish( IRA) & Italians ( Mafia) were more ingrained in large numbers, both who will continue their lawless criminal ways in what was at that time a continent too large to control/manage, who had a short history of extremist religious settlers who were deported from the UK and a few weeks later deported in the same way from Holland because of their extremist ways and civil wars, a country who at that time required people to develop and built it, so should the USA have vetted them, sure but what the USA needed were people/bodies which was more of a priority to them than vetting.........and you could say the same about Australia which was a British penal colony where all and any convicts were sent and they haven't had the same issues as the USA

Sure, but better late than never, yes?