The National Popular Vote Interstate Compact (NPVIC) is an agreement among a group of U.S. states and the District of Columbia to award all their electoral votes to whichever presidential candidate wins the overall popular vote
As of July 2019, it has been adopted by fifteen states and the District of Columbia. Together, they have 196 electoral votes, which is 36.4% of the Electoral College and 72.6% of the 270 votes needed to give the compact legal force.
The current Electoral College system allows a candidate to win the Presidency while losing the popular vote, as happened in the elections of 1824, 1876, 1888, 2000, and 2016. (The 1960 election is also a disputed example.
In the 2000 election Al Gore won 543,895 more votes nationally than George W. Bush, but Bush secured 5 more electors than Gore, in part due to a narrow Bush victory in Florida
In the 2016 election, Hillary Clinton won 2,868,691 more votes nationally than Donald Trump, but Trump secured 77 more electors than Clinton, in part due to narrow Trump victories in Michigan, Pennsylvania, and Wisconsin (a cumulative 77,744 votes).