It should be allowed without restriction as long as the foriegners enter the country legally. People from many countries come to the United States to seek a better life and better opportunities. We shouldn 't deny the life they want in the states. Placing restrictions on them only makes things harder for them.
Because we have so many different countries and governments, allowing immigration without restriction will never happen and to a degree, that seems sensible to me. I would love to live in a world where it was possible to immigrate freely because I would make it a point to live in several different areas of the world throughout my life.
Immigration is a privilege and not a right, and it has been limited in the country since the 1800s. People who want to come to the United States should do so legally. Making immigration completely unlimited could put an economic strain on the U.S. There are also limits on what type of people can immigrate; for example, someone suspected of having terrorist leanings may be deported.
I do think the immigration process should be streamlined and made much more easy, with much less paperwork, and less hoops to jump through. It's not just the United States that makes immigration hard, but several countries around the world do the same thing, and it only seems to be getting harder.
It is my opinion that immigration should not be allowed without restriction. Our nation is currently inhabited by a united people with a democratic government, and immigration without restriction would make this system fall apart. Immigration should be restricted to ensure that our nation does not become over populated in coming years.