I have my phone set to reject any incoming calls from my CO prefix (area code and first 3 digits) because I don't know anyone with the same CO prefix and that's what spammers spoof most often.
It's not just you, it's everyone in the USA. There has been numerous robo calls throughout the year and the only way to fight it is to block unknown calls in your setting or download a robo call blocker. I use Truecaller (Available both iOS and Android) and it has blocked many spam calls since then. I still get some spam calls but rarely now.