Although this depends slightly on what period you're referring to during this time, the best answer would be that "Immigrants" made up the largest percentage of workers in American industry during the late nineteenth century, since the economy had shifted towards industrial output as opposed to agrarian output.
Some things a community could do to help increase the life expectancy for their citizens are to fund new athletic programs, serve healthier foods at schools and workplaces, and provide free health screenings.
