Who's the most vulgar, racist, thin-skinned, vituperative U.S. president?

As a historian of Reconstruction, I've always believed that it was Andrew Johnson. However, considering his astonishing first year in office, I'd contend President Donald Trump may soon own this dubious distinction. [...]

Through bold assertion of executive authority, Johnson quickly reconstructed state and local governments in the South. Because African-Americans were excluded from the process, these regimes were controlled by Southern whites, most of whom had been loyal Confederates. Predictably, they adopted laws designed to keep African-Americans in a servile position.

Southern officials also stood by and even abetted whites who unleashed a wave of violence against former slaves. For example, in July 1866, New Orleans police participated in a massacre that left 37 African-Americans and white Unionists dead and more than 100 wounded.

Unlike today's Republicans, most of whom have become more loyal to Trump, Reconstruction-era Republicans pushed back against Johnson. They viewed emancipation as a crowning achievement of Union victory and were determined to ensure that former slaves enjoyed the fruits of freedom. Although they hoped to avoid conflict with the president, in early 1866, they adopted measures designed to establish color-blind citizenship and protect former slaves from injustice.

Like Trump, Johnson's instinct was to attack rather than negotiate. A states' rights Democrat and proponent of white supremacy, Johnson rebuffed Republicans' efforts at compromise. He responded to Republican civil rights legislation with scathing veto messages. In September 1866, he toured the North, leveling personal attacks against congressional leaders and seeking to rally voters against them in the midterm elections.

Growing up poor and illiterate, Johnson had developed a deep hostility for African-Americans, believing that they looked down on people like him. [...]

While lauded by white Southerners, he was reviled by African-Americans and most Northerners for disgracing the office of the presidency. Thomas Nast, the popular political cartoonist, lampooned him, the press chastised him and private citizens expressed their disgust.

Commenting on Johnson's electioneering tour of the North, Mary Todd Lincoln said acidly that his conduct "would humiliate any other than himself."

Congressional Republicans overrode Johnson's vetoes and tied his hands on matters of policy. In 1868, the House of Representatives voted to impeach him but the Senate fell one vote shy of the two-thirds majority necessary to remove him from office.

As his term came to an end in 1869, his successor, Ulysses Grant, refused to ride to the inauguration in the same carriage as the disgraced Johnson, who then declined to attend the ceremony.