To the extent that there had been any weakness in Democratic turnout so far this year, it had been among black voters. In Georgia’s Sixth Congressional District, for instance, black turnout barely eclipsed midterm levels even as all other voters surged well past it. A similar pattern appeared in Virginia. In majority-black Petersburg, the turnout was even lower than it was in 2013, even as turnout surged in Northern Virginia.

But in Alabama, black turnout was far stronger than white Republican turnout, based on county-level data and the exit polls. Black voters probably represented an even larger share of the electorate than they did in 2012 or 2008.

A reasonable initial estimate is that black turnout probably reached 30 percent above 2014 levels — that’s the increase in total votes, not the overall turnout rate. Statewide, the turnout increase for all voters was just 13 percent.

It will be easier to make a more precise estimate of the increase in black turnout when precinct-level data becomes available in Alabama’s diverse, urban centers or when the voter file becomes available.

At the same time, Mr. Jones benefited from an extremely favorable turnout pattern among white voters, especially along educational lines.