Wow, I never realise it was an issue in the US, silencers are a common sight at the rifle range I go to.
Silencers are heavily regulated in the United States, the same as machine guns. Some states outlaw them completely. In the U.S., there is no “right” to a suppressor. You have to fill out copious paperwork, send it to the local police official, who can arbitrarily veto it, have your fingerprints taken, send $200 and the paperwork to the federal agency, the BATFE, and then have them take about six months to a year and a half to approve it.
If you want more than one, you have to do the above all over again.