February has been designated Black History Month by every president since Gerald Ford, who in 1976 called on the public “to seize the opportunity to honor the contributions and legacy of African Americans across U.S. history and society.”

What Ford didn’t say is that we need this opportunity because Black people have been left out of the history that’s taught in the other months of the year for a long time. With occasional exceptions, there is a 400-year hole in American history that makes it harder for us to understand our shared past, who we are as a nation and where we are headed.

Black History Month could not come at a better time this year, when history itself is under attack.

Just as we are called to honor people who had to overcome oppression, legislators in multiple states are passing laws that make it a crime to teach about the oppression itself. In Tennessee, it’s illegal to teach children that Black Americans were enslaved for centuries and then denied full citizenship through racist laws and institutions if it makes white students “feel discomfort, guilt or anguish.”

This is not just happening in the South. Just down the highway from us, the New Hampshire legislature is considering a bill that would update the Teacher Loyalty Act, a Red Scare relic that prohibits communist indoctrination in the classroom.

The new version would also outlaw teaching “any doctrine or theory promoting a negative account or representation of the founding and history of the United State of America …,” including “teaching that the United States was founded on racism.”

These laws aim to protect what their authors see as the truth about America, but you can’t protect the truth by hiding the truth. Racism does not make America unique. Dig deep enough and you can find discrimination and prejudice on virtually every spot on the globe.

But what’s different about America is our capacity to change. What began as an all-white oligarchy enriched with captured land and slave labor has moved ever closer toward an ideal of multiracial democracy using the tools embedded in our Constitution.

Consider this: The emancipation of 4 million enslaved people at the end of the Civil War is one of the greatest liberations in human history. But it doesn’t mean as much if you pretend that the previous 250 years of chattel slavery hadn’t been enshrined in the new country’s law books and balance sheets.

And the achievements of the civil rights era, from the Supreme Court outlawing school segregation in 1954 to Congress passing the Voting Rights Act in 1965, are great only if you know that for a century after the Civil War an apartheid state existed in the old Confederacy, where unreconstructed rebels used bogus laws and lynching to deny freedom and opportunity to their Black neighbors.

Racial bias was woven into this country’s institutions from the beginning, affecting access to housing, health care, education and wealth creation for generations. You can’t fully appreciate the achievements of Black Americans like Thurgood Marshall, Rosa Parks or Fannie Lou Hamer without understanding the obstacles they faced. Erasing the shameful parts of our shared history erases those heroes and robs all Americans of our true inheritance. When it’s our turn to stand up for what’s right we need their example.

Stripping the bad parts out of the American story doesn’t just make it less inspiring – it’s also dangerous.

It’s been said that those who do not remember the past are condemned to repeat it. Americans of all races and backgrounds should learn Black history so we can all understand how some otherwise good people could behave like monsters or why people who knew better could stand by and do nothing.

Let’s  seize this opportunity to remind ourselves that the American story can’t be told without Black history. We should embrace it, and understand what it has to tell us, not just this month but always.