in the second half of the 19th century, the u.s. government allowed more immigrants into the country mainly because responses a more soldiers were needed in the american military.more soldiers were needed in the american military. b the world war in europe was causing millions to flee their homelands.the world war in europe was causing millions to flee their homelands. c western territories needed more settlers to explore for gold and silver.western territories needed more settlers to explore for gold and silver. d industries needed an increasing amount of cheap labor.