Illegal immigrants provide a cheaper alternative and extra labor to the US work force, however, that is not exactly a "positive benefit".
The only helpful benefit that brings is to a private or commercial company, which allows them to not only skirt around having to pay extra for employee security, but also their benefits.
There are many more cons to illegal immigrants coming in to the US. Most of them are denied because of criminal history or illegal possessions, which, if allowed across the border can be detrimental to the societal structures of the US. Another con can be that they would take over jobs that are typically held by US citizens, prompting the US government to have to work harder in providing services to help prop up US families to survive, which in turn drives up the taxes. Still another can be the misuse of support and rights given to legal immigrants and citizens, including the usage of US benefit programs, the usage of their information in a illegal manner, such as use in ballots, and many others.
Illegal immigration takes away from the US citizens, and should be harshly dealt with. There are channels in which one can legally immigrant into the US, as well as channels for refugees in which one can take if the immigration process takes too long. However, illegal crossing the border is a crime, and should be dealt with like all other crimes. There are not much benefits in which a illegal immigrant can bring compared to the likely detriments that would most likely occur.
