The number of people using the 'hidden internet' in America has risen by 60% since Edward Snowden's fresh spying revelations.
The ex-CIA employee revealed on August 1 that the US Government has a secret surveillance programme providing access to millions of people's emails, online chats and browsing histories.
XKeyscore lets National Security Agency (NSA) analysts access this information without any prior authorisation, according to training guides for the programme leaked to the Guardian by the former CIA employee.
Figures published by Tor, which aims to keep web activity anonymous by sending traffic through multiple encrypted layers, show that its popularity is rising sharply.
The total number of Americans using Tor jumped from 92,212 on August 1 to 149,847 on August 24, according to the data.
In the UK, the number of people using the service rose from 16,375 to 36,520 over the same period.
Service provider Freedom Hosting, which hosts websites via Tor, has come under fire recently for allegedly helping the proliferation of child abuse images.
And it recently became the victim of hackers suspected to be working for a US law enforcement agency.
This bug is then able to load malware onto the computers of Freedom Hosting sites' visitors.
Snowden, who has been granted asylum by Russia, is wanted in the US for leaking documents revealing the extent of its surveillance programme, Prism, which the US claims is vital in the fight against terrorism, but which has been criticised for its intrusion into people's privacy.