It’s Black History Month. So it’s time to talk about Frederick Douglass, Harriet Tubman, the Rev. Dr. Martin Luther King Jr . . . and also Tom Watson.

Watson was a leader in the People’s Party, which called on blacks and whites to unite against rich bankers and landowners. “You are made to hate each other because upon that hatred is rested the keystone of the arch of financial despotism which enslaves you both,” Watson declared in 1892. “You are deceived and blinded that you may not see how this race antagonism perpetuates a monetary system which beggars both.”

But Tom Watson was white, not black. So he isn’t the kind of person we tend to discuss during Black History Month, which focuses almost exclusively on the lives of African Americans.

That’s a mistake. Of course we should use this month to emphasize black contributions and achievements, which are too often ignored or downplayed in our schools and colleges. But we must not neglect key white allies like Watson, who remind us that black and white struggles for justice have always been intimately linked.

And that’s a message I’d like every American — but especially every white American — to hear this February, at a hugely polarized moment in our national history. ...