In 1873, Lynch was elected as the first African-American Speaker of the Mississippi House of Representatives; he is considered the first Black man to hold this position in any state.

After Democrats regained power in the Mississippi legislature, they disenfranchised much of the majority-black electorate by raising barriers to voter registration.

Beginning with the end of federal Reconstruction in 1877, Lynch wrote and published four books analyzing the political situation in the South.

To protect his family, Patrick Lynch planned to buy Catherine and their mixed-race sons from the Tacony Plantation owner.

Lynch could no longer afford to post the $1,000 bond required by the legislature for each person in his family in order to free them.

He thought the city would be a good place to live, as he had learned that it had a large population of free people of color.

Although too young to participate as a delegate, he attended the state's constitutional convention of 1867, studying its developments closely.

In April 1869 at the age of 22, Lynch was appointed by the military governor, Adelbert Ames, as a Justice of the Peace in Natchez.

In his last term, January 1872 he was elected as Speaker of the Mississippi House, the first African American to achieve that position.

[7] At the age of 26 in 1872, Lynch was elected as the youngest member of the US Congress from Mississippi's 6th congressional district, as part of the first generation of African-American Congressmen.

[7] Elections in the state were increasingly accompanied by violence and fraud as Democrats worked to regain political power.

Perhaps his greatest effort was in the long debate supporting the Civil Rights Act of 1875 to ban discrimination in public accommodations.

They feel that they purchased their inheritance, when upon the battlefields of this country, they watered the tree of liberty with the precious blood that flowed from their loyal veins.

They ask no favors, they desire; and must have; an equal chance in the race of life.In 1876 Lynch spoke out against the White League and racial divisions in his state.

As a result of a national Democratic Party compromise, in 1877 the federal government withdrew its troops from the South, and Reconstruction was considered ended.

Future president Theodore Roosevelt made a moving speech nominating Lynch as Temporary Chairman of the 1884 Republican National Convention in Chicago, Illinois.

They left Mississippi the following year, part of the Great Migration to Northern industrial cities, and settled in Chicago.

As the state legislature had disenfranchised blacks by its new 1890 constitution, based on poll taxes and literacy tests,[10] Lynch returned to Washington, DC the following year to set up his law practice.

He also became involved in real estate, as the city became a destination of tens of thousands of rural blacks in the Great Migration, including many from Mississippi.

Lynch wrote a book, The Facts of Reconstruction (1913), and several articles criticizing the then-dominant Dunning School of historiography.

Dunning and followers, many of whom were prominent in major Southern universities, evaluated Reconstruction largely from the viewpoint of white former slave owners and ex-Confederates; they expressed the discriminatory views of their societies.

They routinely downplayed any positive contributions of African Americans during Reconstruction, said they were dominated by white carpetbaggers, and could not manage political power.

(This was in keeping with the disfranchisement of blacks throughout the former Confederacy from 1890 to 1910, and the imposition by state legislatures of racial segregation and Jim Crow law to restore white supremacy.)

Since Lynch participated directly in Reconstruction-era governments, historians consider his book to be a primary source in study of the period.