Cochran's campaign courted black voters, perceiving their unhappiness with his tea party-supported opponent, Chris McDaniel, and his anti-government rhetoric and scathing criticisms of President Barack Obama. Blacks responded by turning out to help give Cochran an almost 7,000-vote win.
The use of Mississippi's open primary to further their agenda showed political maturity by black voters and debunked a longstanding belief that they obediently vote Democratic and not according to their own interests.
They turned out for a primary runoff with no Democratic candidate involved. And they voted Republican even though the smart play for the Democrats would have been to usher McDaniel to victory and create a more winnable contest for Democrat Travis Childers in November.
"I think that Thad Cochran is a shot across the bow to be felt for a long time,'' said the Rev. Jesse Jackson, who was the first minority presidential candidate to win a statewide primary or caucus in 1984 and 1988. "You cannot win in the new South or win in national elections with all-white primaries. This is a new America today.''
Tests of this assertion are coming next month in Alabama and Georgia, also Southern states with large minority populations and open primaries. The Mississippi race may be a harbinger of more strategic voting for minority voters, especially African Americans, said D'Andra Orey, a political science professor at Jackson State University in Jackson, Mississippi.
"This is not a one-time situation,'' Orey said. "Blacks do recognize their power in the vote, and in this particular case, blacks saw that they could actually defeat or be a strong influence, in defeating McDaniel.''
In Mississippi, which is 38 percent black and on track to become the country's first majority-black state, some black voters said they planned to support Cochran, a six-term incumbent, again in November.
Others said they would keep their options open in November or vote for the Democrat, even though they considered Cochran a better choice than McDaniel in the red state.
"I just think that McDaniel did as much for the Cochran turnout in the black community as Cochran people did,'' said Democratic Rep. Bennie Thompson, Mississippi's sole black congressman.
Agitating minority voters may soon prove politically risky anywhere in the nation: the numbers of black, Hispanic, Asian and Native American voters are growing not only in presidential election years but in off-cycle elections as well, according to the U.S. Census Bureau.
In presidential election years, the percentage of black voters eclipsed the percentage of whites for the first time in 2012, when 66.2 percent of blacks voted, compared to 64.1 percent of non-Hispanics whites and about 48 percent of Hispanics and Asians.
The number of African American and other minority voters has also been increasing during off-cycle, non-presidential elections. For example, in the 2010 congressional and statewide elections, 47.8 percent of non-Hispanic whites, 40.7 percent of blacks, 21.3 percent of Asians and 20.5 percent of Hispanics voted.
But the only groups to increase their numbers were blacks and Hispanics, who voted at 38.6 percent and 19.3 percent respectively in 2006 congressional and statewide elections. The white and Asian participation rate dropped during that same time period from 50.5 percent and 21.8 percent.
And black participation in off-year elections has been steadily increasing since 1994, when it was 37.1 percent. In 1998, it 39.6 percent, in 2002 39.7 percent and a slight dip in 2006 at 38.6 percent. No other group showed a similar increase.
Black voting increased during the Mississippi GOP primary. Statewide turnout increased by almost 70,000 votes over the June 3 primary, with turnout in majority-black counties growing by 43 percent, while in counties where blacks are less than a majority, it grew 17 percent.
Carol M. Swain, a law and political science professor at Vanderbilt University in Nashville, doubted those voters would become Republicans but said they could become swing voters in some races. "I believe they may have purchased some influence with the Republican establishment that could benefit blacks in the long run,'' Swain said.
Democrats, in return, plan to address more African American issues in upcoming campaign, but they have been warned not to take those votes for granted.
At a recent meeting with black journalists and advocates, several U.S. senators were warned that some black voters had noticed that Democrats had no problem talking about veterans' issues, women's issues or LBGT issues, but seemed hesitant to talk about and address black issues on the Senate floor.
Sen. Tim Kaine, D-Virginia, said he could understand how "off-putting'' it could be that Democrats "are all about equality and all about the big tent, but we're talking about other folks and not us,'' a loyal voting base.
"I hadn't really thought about our strong advocacy on these diversity issues actually could have an undercurrent of `We must not be that important because you're not talking about us the same way,''' Kaine said.
Recognition of that can only be a good thing for minority voters, Swain said.
"The positive thing to come out of this is that more white candidates and incumbents will campaign among black voters, and maybe they will deliver more,'' she said.