The recurring history of segregationist subversion in the US

Heather Cox Richardson in her Facebook post of July 2 refers to the unfortunately successful to disenfranchise African-American voters which set the foundation for 90 years of "legal" racial voter suppression and segregation after the series of events she describes:

The association of sitting Congress members with someone who was apparently part of an insurrection is particularly audacious at a moment when the House of Representatives is in the process of forming a select committee to investigate that series of events.

Once before, in 1879, a political party behaved in a similarly aggressive way, trying to destroy the government from within. Then, too, Congress members took an extremist position in order to try to steal the upcoming presidential election. They hoped to win that election by getting rid of Black voting.

In that case, it was the Democratic Party that was leading the overthrow of the democratic Reconstruction governments in the South.

There's is a widely-accepted conventional date for  when Reconstruction was successfully overthrown. The editors of History.com date the end in 1877. "The Compromise of 1877 was an informal agreement between southern Democrats and allies of the Republican Rutherford Hayes to settle the result of the 1876 presidential election and marked the end of the Reconstruction era." (Compromise of 1877 1172772019)

But James Oakes (In response to: An Unfinished Revolution from the December 5, 2019 issue New York Review of Books 03/12/2020 issue) write about:

... a concern I’ve long felt about the conventional use of 1877 as the year Reconstruction ended; 1875, the year Republicans lost control of the House of Representatives to the Democrats, strikes me as a better date for the effective end of federal Reconstruction policy. But in the Southern states, Reconstruction in many ways continued as long as blacks could vote and hold office, which is why another reasonable date for the end of Reconstruction might be 1890, when the Mississippi Plan inaugurated the sweeping policy of disfranchisement that eventually engulfed most of the South. With good reason William Archibald Dunning [founder of the neo-Confederate "Dunning School" of history] described disfranchisement as “the undoing of Reconstruction.” Either date — 1875 or 1890 — would probably be better than 1877, when ... not much of anything actually happened. (my emphasis)

Eric Foner also alludes to the lack of any one clear moment that definitively marked the end of Reconstruction (Historian Eric Foner On The 'Unresolved Legacy Of Reconstruction' NPR 06/05/202):

Reconstruction is usually dated as 1865, when the Civil War ends, to 1877, when the last federal troops are removed from the South or, strictly speaking, from political participation in the South. But actually, in my book and other writings, we now really begin Reconstruction during the Civil War because efforts to remake Southern society really begin even when the Union army occupies parts of the South during the Civil War. So it begins somewhere in the early 1860s. And then it doesn't just end in 1877. It goes - in some places, these rights that blacks had achieved, are still enjoyed into the 1890s. (my emphasis)

But none of this should divert anyone's attention to the central role that voter suppression played in establishing the segregation system that succeeded Reconstruction. At least the intellectual architects of the Republican's neo-segregation efforts currently underway in various Republican-run states, Congress, and, of course, the Supreme Court. In an article that accepts the conventional dating of 1876-7 for the end of Reconstruction ("America's Second Sin" Time 04/15/2019), Henry Louis Gates Jr. writes:

In addition to their moves to strip African Americans of their voting rights, “Redeemer” [anti-democracy white supremacist] governments across the South slashed government investments in infrastructure and social programs across the board, including those for the region’s first state-funded public-school systems, a product of Reconstruction. In doing so, they re-empowered a private sphere dominated by the white planter class. A new wave of state constitutional conventions followed, starting with Mississippi in 1890. These effectively undermined the Reconstruction Amendments, especially the right of black men to vote, in each of the former Confederate states by 1908. (my emphasis)