If anything became crystal clear tonight, it’s the stark diversity divide between Bernie Sanders‘ supporters and Hillary Clinton‘s supporters. Her big wins in the South tonight demonstrated that her shellacking of Sanders among black voters in South Carolina on Saturday was no fluke.

The one constant throughout the Democratic primaries and caucuses so far has been that the fewer black voters a state or portion of a state has, the more Clinton struggles. She barely won Iowa, got clobbered in New Hampshire, and got clobbered tonight in MinnesotaColoradoOklahoma and Vermont, but absolutely destroyed Sanders in TexasGeorgiaVirginiaAlabamaSouth CarolinaTennessee and Arkansas. And while Massachusetts is pretty white, it’s more diverse than Iowa or New Hampshire; the small percentage of Massachusetts voters who are black very well could have been the difference for her in that state tonight. Clinton won the cities; Sanders won the lily-white rural areas.

I’ve said it before, and I’ll say it again. Any candidate who cannot win a significant number of votes in diverse communities cannot win the Democratic nomination. There is no way to put together a coalition in the Democratic Party that doesn’t include voters of color. If Sanders can’t start making serious inroads into communities of color very soon, he has no chance of reversing his fortunes.