With the abolition of slavery in 1865, voting rights for black men became an important and controversial political issue. In the spring of 1867, Congress required the former Confederate states to enact black manhood suffrage as a stipulation for readmission to the Union. With 10-15% of the white electorate disfranchised for past Confederate affiliation, black men constituted the majority of voters in several Southern states, with 70-90% casting ballots. They were the key Republican constituency in the South. In the North, black men could vote only in four Midwestern states and five of the six New England states (not Connecticut).

Radical Republicans such as Senator Charles Sumner of Massachusetts pushed for the adoption of black voting rights on the grounds of both justice and political necessity. Harper’s Weekly editor George William Curtis urged the New York State Constitutional Convention in 1867 to equalize voting rights because "civil rights were a mere mocking name until political power gave them substance." His efforts were unsuccessful, and the issue was also defeated that year in popular referenda in Kansas, Minnesota, and Ohio. The 1868 Republican national platform strongly endorsed the congressional mandate of black manhood suffrage in the former Confederacy, while hypocritically asserting that it was up to individual states in the rest of the country.

The 1868 elections, however, gave Republicans a political incentive to push for nationwide voting rights for black men. Republican Ulysses S. Grant was elected president by a wide margin in the electoral college, but a closer margin in the popular vote (53-47%), with the tally in several states being extremely close. Democrats picked up seats in the U.S. House of Representatives, while threats and acts of violence against black and white Republicans in Georgia and Louisiana allowed those states to elect Democratic legislatures. Iowa and Minnesota voters passed black manhood suffrage referenda, but none of the five border states (former slave states loyal to the Union) and only eleven of twenty-one Northern states permitted black men to vote. Almost 17% of the nation’s black population lived in those states.

Blacks in New York and other Northern states petitioned Congress for their voting rights, and Southern blacks voiced their support. The outgoing Republican Congress decided to take action before the incoming Congress, with it smaller Republican majority in the House, was sworn into office. Various proposals for a constitutional amendment were submitted in both houses in January and February 1869, but the final version was a moderate compromise which failed to ban state requirements for voting which were not race-based, such as literary tests. Rather than a positive affirmation, the proposed Fifteenth Amendment stated that the right to vote could not be denied because of "race, color, or previous condition of servitude."

The proposed Fifteenth Amendment passed Congress in February 1869, and then awaited ratification by the constitutionally necessary three-fourths of the states. The New England states, which Republicans dominated, quickly ratified it, but the battle was more difficult in the Mid-Atlantic states. Passage by a Republican-controlled legislature in New York was reversed by the succeeding Democratic-controlled assembly which was elected in the fall of 1869. The New York fly in this cartoon is Democratic governor John Hoffman. Pennsylvania approved the measure in March 1869, but New Jersey defeated it, and Delaware did not give its approval until 1901, decades after it was operative. The latter two states appear as flies in the cartoon, as do the border states of Maryland and Kentucky, which also rejected it.

The three remaining unreconstructed states of Mississippi, Texas, and Virginia complied with the Congressional requirement that they pass the proposed amendment in order to regain admission to the Union. Except for Tennessee, the other Confederate states followed suit by passing the measure. President Grant had to pressure the Nebraska governor to call a special session, but that state and other Midwestern states voted for ratification.

In the West, California (another fly) rejected the amendment for fear it would lead to an "invasion" of Chinese. There was intense prejudice and discrimination in California against Chinese immigrants, who outnumbered blacks in the state by a ten-to-one ratio. Supporters in Nevada, the only state in the Far West to ratify the amendment, convinced enough legislators that "race" meant the African race and would not apply to the Chinese.

In the issue of Harper’s Weekly in which this cartoon appears, an editorial announces that it is probable that the proposed amendment will be ratified. A few weeks later, on March 30, 1870, the Fifteenth Amendment officially became part of the U.S. Constitution. As black men gained the vote in the rest of the country, they lost it gradually in the South as Reconstruction drew to a close and state requirements (poll taxes, literary tests, etc.), intimidation, and violence prevented them from casting ballots.

In the North, the white electorate believed that the goals of Reconstruction had been fulfilled with the ratification of the Fifteenth Amendment, so increasingly lost interest in the issue of voting rights. The measure ended up being less important in constitutional law than the Fourteenth Amendment, but the Voting Rights Act of 1965 gave power to the principle embodied in the Fifteenth Amendment.