In the wake of 9/11, the US government passed the Patriot Act, which greatly expanded the government’s surveillance power to spy on its own citizens.
One of the more concerning sections of this bill (Section 215) relates to the US federal government’s ability to look at and confiscate an individual’s personal data held by third parties. (Think of your health records stored at your doctor’s office or your personal browsing data collected by your internet service provider.)
This bill expired in 2015 and was replaced by the USA FREEDOM Act, which was in effect until 2019. Congress continues to re-introduce clones of the Patriot Act to the floor, but there are still many unknowns.
The safest thing you can do to protect yourself from governmental surveillance is to use a VPN.