There are now 26 millennials in congress - a fivefold increase gained in the last midterms. They're governing over Midwestern cities and college towns, sitting on city councils and running for state legislatures. Some of them have been in office for a few years; one of them is running for president. In The Ones We've been Waiting For, TIME correspondent Charlotte Alter defines the class of young leaders who are remaking the nation, and what America will look like when they're in charge.