More than 1,700 congressmen once enslaved Black people. On today’s episode of “Post Reports,” the first database of those slaveholding congressmen. And how those politicians shaped the nation. Read more:For the first seven decades of its existence, Congress returned again and again to one acrimonious topic: slavery. Many of the lawmakers arguing in Washington were enslavers themselves. But until recently, the world didn’t know how many. Last week, The Post published the first-ever list of every slaveholding member of the U.S. Congress. More than 1,700 of them were elected to Congress over a period of well over a century. To create the database, reporter Julie Zauzmer Weil combed through 18th- and 19th-century census records and other documents, including wills, journal articles and plantation records. And while she says that the work is not yet complete, it’s still useful, and powerful.“You can look at a lot of issues through this prism of where we started as a country, and where the people who held power were so often the same people who held slaves,” Julie said. “And what does that mean for us now?”