How does one find places that accept Bitcoin in the US? How does one find companies or stores that accept Bitcoin in the US?
The Bitcoin payment service provider BitPay claims to have 20,000 merchants, both online and physical (brick and mortar), that accept Bitcoin on their system. They have a directory of companies here: https://bitpay.com/directory#/ but they are certainly not the only payment services provider. 

http://coinmap.org/ has a list of almost 5000 brick and mortar locations that accept Bitcoin (not tied to any particular payment service provider).

Interestingly enough, just yesterday Yelp.com officially announced a new feature that allows businesses to specify whether or not they accept Bitcoin! This means that soon the Yelp API will also become a very valuable source of Bitcoin acceptance information. 

Major retailers like Overstock.com and TigerDirect have also began accepting Bitcoin!