title: Determine if a given lat/long is within the borders of the USA
body: <p>How can I determine if a given lat/long is within the borders of the USA? I'd like for backend code to behave in one way if within the US and another outside of the USA. Due to requirements of the application, IP Geolocation is not an option here.</p>
  
  <p>Ideally I'd like this to happen without hitting an external service.</p>