How do we have more cases then china, when they have 4x our population?

We report more.: In the US, testing is important but also reporting. Reporting not just to public health but to the CDC. They take this information and report to the public to show them what is happening with the numbers. Although this may still be an undercount its significant enough to look at trends. China has a system where reporting to the public doesn't need to take place. Reporting to the government does