A congressional race in North Carolina that seemed to be settled on election night was reopened last week amid allegations of absentee ballot fraud. The Republican candidate, Mark Harris, has a 905-vote lead over the Democrat, Dan McCready.

Here’s what we know, and what we don’t know.

What we know

• The North Carolina State Board of Elections certified election results last week in 12 of the state’s 13 congressional districts. But it voted unanimously not to certify the results in the Ninth District — where the Republican candidate, Mark Harris, led the Democrat, Dan McCready, by less than half a percentage point — because of absentee ballot irregularities.

• Bladen County, a largely rural county in the district, recorded the state’s highest rate of absentee ballot requests: 7.5 percent of registered voters, compared with less than 3 percent in most counties. An unusually large number of them, 40 percent, were never returned. Even more, 62 percent, were unreturned in neighboring Robeson County. No other county had an unreturned rate higher than 27 percent. And according to an analysis by The News & Observer, the unreturned ballots — especially in Robeson County — were “disproportionately associated with minority voters,” who tend to vote for Democrats.

• Mr. Harris won 61 percent of submitted absentee ballots in Bladen County, even though registered Republicans accounted for only 19 percent of the ballots submitted. To do that, he would have had to win essentially every independent who voted absentee, as well as some registered Democrats. In every other county in the district — even strongly Republican ones — Mr. McCready won the absentee vote.