Many contemporary controversies over issues like voting rights and the scope of the government have their origins in the period following the Civil War. That era, known as Reconstruction, is one of the most contentious in this nation’s history, and also one of the most misunderstood.

Congress can help fix that by passing the Reconstruction Era National Historical Park Act before the end of the year. The bill, passed by the House in September and now under consideration in the Senate, would empower the National Park Service to connect Reconstruction sites all around the country; encourage visitors to talk about Reconstruction at local historical sites; and help convey the full story of how America was remade after the Civil War.

Reconstruction started in the early days of the Civil War. As United States forces entered the South, enslaved African Americans immediately pressed for freedom. They escaped to Union lines, demanded pay for their work, petitioned for their rights and served the Union war effort as laborers and soldiers. Some four million African Americans built new lives in freedom during the postwar Reconstruction era — reuniting families separated by slavery, building churches, founding schools and serving in government.

From 1865 to 1870, Congress passed, and the states ratified, the 13th, 14th and 15th Amendments, which permanently transformed the country. These Republican-led initiatives promised freedom, citizenship, due process and equal protection to everyone on American soil, and also prohibited racial discrimination in voting. These constitutional changes were so momentous that, in 2017, President Barack Obama called Reconstruction the nation’s Second Founding.