Immigration is always beneficial to both America and its citizens.
Just look at business success and job creation: 55% Of America's Billion-Dollar Startups Have An Immigrant Founder (Source: Forbes, https://www.forbes.com/sites/stuartanderson/2018/10/25/55-of-americas-billion-dollar-startups-have-immigrant-founder/?sh=36441aaa48ee)
From a philosophical perspective, nothing can be "always" anything. If the topic was "Immigration is almost always beneficial to both America and its citizens." (or something of the sort), I would argue for pro.