The Guardian US edition and the Washington Post have both won the Pulitzer Prize for public service for their coverage of secret surveillance by the US National Security Agency.
Their reporting was based on documents leaked by former NSA contractor Edward Snowden, who revealed details of global electronic surveillance by the US spy agency.
The board said the reporting by the Guardian US helped spark debate about the relationship between the US government and the public over issues of security and privacy.
The Washington Post was commended for explaining how the disclosures fit into a larger framework of national security.
Reporting on the leaks, which began last June, triggered international debate over the limits of government surveillance and prompted President Barack Obama to introduce curbs on the spying powers of the National Security Agency earlier this year.