This Breitbart article shows that at least 2.5 million immigrants from Islamic countries currently live in the United States, with more than 1 million of them arriving between 2000 and 2013.
This Breitbart article article projects that Hillary Clinton would likely end up permanently resettling as many as 214,000 Muslim immigrants in the U.S during the first year of her administration if she wins the presidency, with the total amount of Islamic immigrants during her first term in office being almost 1 million if she would continue that trend for each of the four years.
And this Breitbart article explains the issue of many potentially radical Muslims being allowed into the U.S. due to its lax immigration policies. It explains that adequate vetting has not been done on the many Somali and Iraq refugees which have been allowed into the country.