Seeking a better life.

Long ago, the US had vast lands with few people. So immigrants were welcomed. Some of low education were desired to do the work that few wanted to do. Others were welcomed for the skills they brought to our land...Doctors, machinists, teachers, tradesmen and women of all types.
My dad was an immigrant. He was trained as a metal spinner. Came here with cash, a job and apartment pre-arranged. Worked hard and started his own factory eventually.
Now around the globe developed countries have large populations that have grown over decades and more. But, there are countries that the people who wish to better themselves, get knocked back by criminals, warlords, crooks, dictators, thieves, murderers, radical religious gangs and even just an earth that defies them thriving.
These people often are limited in education and skills. Like locusts, they travel in search of food. Some do have a work ethic and think as in the days of old, wealthy nations have lots to spare and room for them. But, many are looking for a free ride. They are lied to by trafficers to save up money that they could better themselves with to get smuggled to those well off nations. Then figure they will be cared for. Even tho there are natives in those countries who aren't.
We have had influxes of refuges from countries the wealthy fought wars in. Often they were helped because they fought along side with us. They came to these countries, took advantage of the possibilities and worked hard, contributed to those lands and thrived. They made their children realize they now were a citizen of that country and to learn the language and customs and improve themselves more than the parents even did.
I see a situation now where third world countries think all they need to do is head north and find a free ride. People with minimal skills that are suited to their country but of little or no use to the northern lands. They will be the new low wage workers doing the jobs no one wants. Or welfare dependents or homeless.
I see nothing of what the flood of people from the south of the globe are accomplishing. Yet our leaders want to provide for them. I do see what the Afghans are doing in our military camps. They are setting up schools to teach English, organizing, putting together activities for the children and attempting to provide structure to prepare for inclusion to our country.
Now which group should we welcome and which should be turned back?