Once firmly in Republican control, suburbs are increasingly politically divided — a rare common ground shared by Republicans and Democrats.
As such, they are poised to decide not just who wins the White House this year but also who controls the Senate and the contours of the debate over guns, immigration, work, schools, housing and health care.
The reasons for the shift are many. Suburbs have grown more racially diverse, more educated, more economically prosperous and more liberal.
But demographers and political scientists are just as likely to point to another trend: density. Suburbs have grown more crowded, looking more like cities and voting like them, too.