Flags flew at half mast, schoolchildren recited the “Gettysburg Address” and for a few hours on April 15, America paused to remember that a century and a half ago this country lost its 16th president to an assassin’s bullet.

Now, Americans can finish with the pause and begin to fully honor Lincoln.

The place of beginning is with an embrace of the work of reconstruction that was imagined when Lincoln lived but that is not—even now—complete.

President Obama proclaimed April 15 as a National Day of Remembrance for President Abraham Lincoln, declaring, “Today, we reflect on the extraordinary progress he made possible, and with one voice, we rededicate ourselves to the work of ensuring a Government of the people, by the people, for the people, shall not perish from the earth.”

Obama was right to focus on Lincoln’s great preachmenton behalf of American democracy. It directs our attention toward the mission to which small “d” democrats of all partisanships and ideologies must rededicate ourselves.

One hundred and fifty years after the moment when a still young country saw the end of a Civil War and the assassination of a president, the events of April 1865 continue to shape and challenge the American experience.

With Lincoln’s death, an inept and wrongheaded vice president, Andrew Johnson, succeeded to the presidency. Had it been left to Johnson, who vetoed the Civil Rights Act of 1866, the progress extending from the great sacrifices of the Civil War would have beenimperiled. But the rough outlines for securing the victory were not left to a president. They were enshrined in the US Constitution.

Three amendments to the founding document were enacted during the five-year period from 1865 to 1870. These “Reconstruction Amendments”were transformational statements—even if their promise has yet to be fully recognized or realized.

The first of the amendments addressed the great failure of the founding moment: a “compromise” that recognized—and effectively permitted—human bondage.

The Thirteenth Amendment to the Constitution affirmed that “Neither slavery nor involuntary servitude, except as a punishment for crime whereof the party shall have been duly convicted, shall exist within the United States, or any place subject to their jurisdiction.”

Those words confronted the indefensible “Three-Fifths Compromise,” which was outlined in Article 1, Section 2, Paragraph 3 of the Constitution as it was framed in 1787. That paragraph did not speak specifically of slavery, but instead referred to two groups of Americans: “the whole Number of free Persons” and “all other Persons.”

The 13th Amendment was an essential step toward an official embrace of Thomas Jefferson’s “immortal declaration”of 1776—that “all men are created equal.”

But it was not enough.

To the 13th Amendment of 1865 was added the Fourteenth Amendment of 1868, which confirmed that “No State shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States; nor shall any State deprive any person of life, liberty, or property, without due process of law; nor deny to any person within its jurisdiction the equal protection of the laws.”

The 14th Amendment, remarkable in its clarity and detail, provided for due process and equal protection under the law.

But it was not enough.

To the Thirteenth Amendment of 1865 and the Fourteenth Amendment of 1868 was added the 15th Amendment of 1870, which avowed that “The right of citizens of the United States to vote shall not be denied or abridged by the United States or by any State on account of race, color, or previous condition of servitude.”

Congress was given the power to enforce these articles by appropriate legislation.

But that was still not enough, as became obvious with the collapse of Reconstruction and the establishment of “Jim Crow” segregation in states that had been part of the Confederacy. With these ruptures came overt discrimination against voting rights.

It took more than a century of litigation, boycotts, protests and marches to restore the promise of equal protection and voting rights.

But that was not enough.

Despite the protections delineated in the Civil Rights Act of 1964 and the Voting Rights Act of 1965, as well as the Twenty-Fourth Amendment to the Constitution (which in 1964 formally banned poll taxes), headlines remind us that the right to vote is “still threatened.” The US Supreme Court has mangled the Voting Rights Act, and the Congress has failed to repair the damage done. The Brennan Center for Justice has determined that at least 83 restrictive bills were introduced in 29 states where legislatures had floor activity in 2014, including proposals to require a photo ID, make voter registration more difficult, reduce early voting opportunities, and make it harder for students to vote.

“The stark and simple truth is this—the right to vote is threatened today—in a way that it has not been since the Voting Rights Act became law nearly five decades ago,” said President Obama.

The great American process of forming a more perfect union is far from complete. The events of 150 years ago were not the end of anything. They were a pivot point that took the United States in a better direction. But the was incomplete, and insufficient to establish justice. So the process continues.

That is why Congressmen Mark Pocan, D-Wisconsin, and Keith Ellison, D-Minnesota, have proposed to amend the Constitution to declare clearly and unequivocally that

“SECTION 1: Every citizen of the United States, who is of legal voting age, shall have the fundamental right to vote in any public election held in the jurisdiction in which the citizen resides.

“SECTION 2: Congress shall have the power to enforce and implement this article by appropriate legislation.”

The Pocan-Ellison amendment will not, in and of itself, form a more perfect union. But it provides a tool for those who understand that we best honor our history by recognizing unmet promises—and seeking, finally, to keep them.

“A core principle of our democracy is the ability for citizens to participate in the election of their representatives,” explains Pocan. “We have seen constant attempts by some states to erode voting rights and make it harder for citizens to vote. This amendment would affirm the principle of equal participation in our democracy for every citizen. As the world’s leading democracy, we must guarantee the right to vote for all.”

Take Action: Make Voting Easier in Your State