we had a birth of 3 wats in the 1980's el salvador, guatemala and nicaragua. guatemala received 1,000's of m 16's under a fundamentalist dictatorship, nicaragua had to fight the contras and landmines in its northern border with honduras where the contras were stationed, and el salvador took delivery of us made helicopters and some military advisers.
these wars were ended in the early 1990's by agreements on both sides
durings these times a sanctuary movment developed with 2 or 3 churches hiding and caring for a few people from the 3 countries
the travelers were men and woman in their 20's were without kids and cane from zones of oppression even violence.
this was done in part clandestinely but will be a large tragedy if trump orders border patrol to deliver the people caught into sanctuary zones. The times are very different in 2019 than year 1986. their is still oppresion in these 3 countries but their is no large wars.
countries such as palestine, kurdish iraq and kurdish turkey as well as african countries and places such as sri lanka and burma are not invokved in the underground economy that involves workers and families. they come legally and are checked in for criminal background, id and health checks to prevent outbreaks in food places, in chuches or in living spaces.
immigration is important, but remeber all of the rest of the population living here, working, raising family and contributing taxes to the different institutions such as schools, clinics, roads, std clinics,recyling, garbage removal and sewers