Registered Democrats have returned 1,153 more ballots than Republicans in Iowa House district 82, as of today. The news will encourage supporters of Democratic nominee Phil Miller, though a strong election-day turnout by Republicans could still win the race for the GOP's Travis Harris. In the high-profile 2009 special Iowa House election covering some of the same territory, Democrat Curt Hanson led by about 1,000 early votes and ended up winning by 107.
This table is based on figures I received from elections office staff in Davis, Jefferson, and Van Buren counties. The numbers include absentee ballots returned through the mail as well as those submitted by citizens who voted early in person at the county auditor's office through August 7.
Absentee ballots received in Iowa House district 82 as of August 8, 2017
County Democrats Republicans no-party voters other total
Davis 311 247 37 1 596
Jefferson 1,585 453 261 9 2,308
Van Buren 168 211 64 n/a 443
district-wide 2,064 911 362 10 3,347
Note that these numbers reflect the party registration of those who cast early ballots, not votes tallied for either Phil Miller or Travis Harris. Some Democrats and Republicans may have crossed party lines, and we can't know how early voters affiliated with neither party split in this election. Also, some of the early ballots have probably been marked for Libertarian Joshua Miller or the Constitution Party's Edward Hee III, who also qualified as candidates in House district 82.
Still, I would guess Phil Miller leads by at least 1,100 votes, which is a lot for Harris to make up today. Total turnout for the 2009 special election was a little more than 8,000 votes; the Republican received more support on election day than Hanson, but not enough to overtake him. Polls opened today at 7 am and will close at 9 pm.
By many accounts, Democratic volunteers knocking doors in House district 82 outnumbered their Republican counterparts during these past few weeks. The GOP campaign on behalf of Harris seems to have been largely grounded in direct mail, television commercials, and some online advertising.
You can watch the Republicans' positive ads about Harris here and here and their attack ads against Miller here and here.
Bleeding Heartland posted the Democrats' positive ads about Miller here and here and the attack ad against Harris here.