For a decade after the Civil War, the federal government sought to make good its promises and protect the rights of the liberated as American citizens. Most critically, in the Civil Rights Act of 1866, Congress created U.S. Citizenship and, in the Civil Rights Act of 1875, Congress guaranteed all American Citizens access to all public accommodations. Then, stretching from 1877 to the end of the century following the close of the Civil War, the federal government did nothing to assure that those rights were respected. Eventually, in Brown v. Board of Education, the Supreme Court started to admit that this was a problem, a clear failure to abide by our Constitution. But the Supreme Court (in Brown II) also made clear that it wouldn’t do anything about it.
So things stood, until a man in high office made it his business to get the federal government again on the side of right, equality, and law. That man was Lyndon Baines Johnson. And while this story could be told in fascinating, exhaustive detail, these are its broad outlines.
Jim Crow’s Defenders
Over much of the century following the Civil War’s close, the American South was an accepted aberration, where the federal government turned a blind-eye to government mistreatment of U.S. Citizens (as well as to the systematic failure of governments to protect U.S. Citizens from mob-rule and racially-tinged violence), and where the highest office White Southerners could realistically dream of attaining was a seat in the U.S. Senate from which such a Southerner could keep those federal eyes blind.,  So, for the decades when it mattered, Southern Senators used their seniority and the procedures of the Senate (most prominently the filibuster, pioneered the previous century by South Carolina’s John C. Calhoun in the early 1800s) to block any federal ban on lynching, to protect the region’s racial caste system from federal intrusion, and to steadily steer federal money into the rebuilding of their broken region. For decades, the leader of these efforts was Senator Richard Russell, a Democrat from Georgia and an avowed racist, if one whose insistence on the prerogatives of the Senate and leadership on other issues nonetheless earned him the unofficial title, “the Conscience of the Senate.”
LBJ Enters the Picture
Then Lyndon Baines Johnson got himself elected to the Senate as a Democrat from Texas in 1948. He did so through fraud in a hotly contested election. The illegal ballots counted on his behalf turned a narrow defeat into an 87-vote victory that triggered his Senate colleagues calling him “Landslide Lyndon” for the rest of his career.
By that time, LBJ had established a number of traits that would remain prominent throughout the rest of his life. Everywhere he went, LBJ consistently managed to convince powerful men to treat him as if he was their professional son. For a few examples, LBJ had convinced the president of his college to treat him alone among decades of students as a preferred heir. For another, as a Congressman, he managed to convince Sam Rayburn, a Democrat from Texas and Speaker of the House for 17 of 21 years, a man before whom everyone else in Washington coward, to allow LBJ to regularly walk up to him in large gatherings to kiss his bald head. And everywhere he went, LBJ consistently managed to identify positions no one else wanted that held potential leverage and therefore could be made focal points of enormous power. When LBJ worked as a Capitol-Hill staffer, he turned a “model Congress,” in which staffers played at being their bosses, into a vehicle to move actual legislation through the embarrassment of his rivals’ bosses. On a less positive note, everywhere he went, LBJ had demonstrated (time and again) an enthusiasm for verbally and emotionally abusing those subject to his authority such as staffers, girl-friends, his wife…, sometimes in the service of good causes and other times entirely in the name of his caprice and meanness.
In the Senate, LBJ followed form. He promptly won the patronage of Richard Russell, convincing the arch-segregationist both that he was the Southerner capable of taking up Russell’s mantle after him and that Russell should teach him everything he knew about Senate procedure. Arriving at a time that everyone else viewed Senate leadership positions as thankless drudgery, LBJ talked his way into being named his party’s Senate Whip in only his second Congress in the chamber. Four years later, having impressed his fellow Senators with his ability to accurately predict how they would vote, even as they grew to fear his beratings and emotional abuse, LBJ emerged as Senate Majority Leader. And in 1957, using as instigation the support of President Dwight D. Eisenhower, a Republican from Kansas, for such a measure and the recent Supreme Court issuance of Brown, LBJ managed to convince Russell both that the Senate must pass the first Civil Rights Act since Reconstruction, a comparatively weak bill, so palatable to Russell as a way to prevent the passage of a stronger one and that Russell should help him pass it to advance LBJ’s chances of winning the Presidency in 1960 as a loyal Southerner. Substantively, that 1957 Act created the U.S. Civil Rights Commission, a clearinghouse for ideas for further reforms, but one with no enforcement powers. The Act’s real power, though, wasn’t in its substance. Its real power lay in what it demonstrated was suddenly possible: where a weak act could pass, a stronger one was conceivable. And where one was conceivable, millions of Americans long denied equality, Americans taught by Brown, in the memorable phraseology of the Reverend Martin Luther King, Jr. that “justice too long delayed is justice denied” would demand the passage of the possible.
The Kennedy Years
Of course, Johnson didn’t win the Presidency in 1960. But, in part thanks to Rayburn and Russell’s backing, he did win the Vice Presidency. There, he could do nothing, and did. President John F. Kennedy, a Democrat from Massachusetts, didn’t trust him, the Senate gave him no role, and Bobby Kennedy, the President’s in-house proxy and functional Prime Minister, officially serving as Attorney General, openly mocked and dismissed Johnson as a washed up, clownish figure. So as the Civil Rights Movement pressed for action to secure the equality long denied, as students were arrested at lunch-counters and freedom riders were murdered, LBJ could only take the Attorney General’s abuse, silently sitting back and watching the President commit the White House to pushing for a far more aggressive Civil Rights Act, even as it had no plan for how to get it passed over the opposition of Senator Russell and his block of Southern Senators.
Dallas, the Presidency, and How Passage Was Finally Obtained
Not long before his assassination in 1963, President Kennedy proposed stronger legislation and said the nation “will not be fully free until all its citizens are free.” But, when an assassin’s bullet tragically slayed President Kennedy on a Dallas street, LBJ became the new president of the United States. The man with a knack for finding leverage and power where others saw none suddenly sat Center Stage, with every conceivable lever available to him. And he wasted no time deploying those levers. Uniting with the opposition party’s leadership in the Senate, Everett Dirksen, a Republican from Illinois, was the key man who delivered the support of eighty-two percent (82%) of his party’s Senators, President Johnson employed every tool available to the chief magistrate to procure passage of the stronger Civil Rights Act he had once promised Senator Russell that the 1957 Act would forestall.
The bill he now backed, like the Civil Rights Act of 1875, would outlaw discrimination based on race, color, religion, or national origin in public accommodations through Title II. It would do more. Title I would forbid the unequal application of voter registration laws to different races. Title III would bar state and local governments from denying access to public facilities on the basis of race, color, religion, or national origin. Title IV would authorize the Department of Justice to bring suits to compel the racial integration of schools. Title VI would bar discrimination on the basis of race, color, or national origin by federally funded programs and activities. And Title VII would bar employers from discriminating in hiring or firing on the basis of race, color, religion, sex, or national origin.
This was the bill approved by the House of Representatives after the President engineered a discharge petition to force the bill out of committee. This was the bill filibustered by 18 Senators for a record 60 straight days. This was the bill where that filibuster was finally broken on June 10, 1964, the first filibuster of any kind defeated since 1927. After the lengthy Democrat filibuster in the Senate, the bill was finally passed 73-27. The Senate passed that Civil Rights bill on June 19, 1964. The House promptly re-passed it as amended by the Senate.
On July 2, 1964, President Johnson signed the Civil Rights Act into law on national television. Finally, on the same day that John Adams had predicted 188 years earlier would be forever commemorated as a “Day of Deliverance” with “Pomp and Parade, with Shews, Games, Sports, Guns, Bells, Bonfires and Illuminations from one End of this Continent to the other[,]” the federal government had restored the law abandoned with Reconstruction in 1876. Once more, the United States government would stand for the equality before the law for all its Citizens.
 Robert Caro has, so far, written four (4) books over as many decades telling this story over thousands of pages. The author recommends them, even as he provides this TLDR summation. Caro’s books on the subject are: The Years of Lyndon Johnson: The Path to Power, The Years of Lyndon Johnson: Means of Ascent, The Years of Lyndon Johnson: Master of the Senate, and The Years of Lyndon Johnson: The Passage of Power.
 Black Southerners, almost totally barred from voting, could not realistically hope for election to any office over this period. It is worth noting, however, that the Great Migration saw a substantial portion of America’s Black population move North, where this was not the case and where such migrants (and their children) could and did win elective office.
 The exception proving the rule is President Woodrow Wilson. Wilson, the son of a Confederate veteran, was born in Virginia and raised mostly in South Carolina. Yet he ran for the Presidency as the Governor of New Jersey, a position be acquired as a result of his career at Princeton University (and the progressive movement’s adoration of the “expertise” that an Ivy League President seemed to promise). Even then, Wilson could only win the Presidency (which empowered him to segregate the federal workforce) when his two predecessors ran against each other and split their shared, super-majority support.