Early voting underway in Tennessee. Here's what you need to know.

After more than a year of campaigning and tens of millions of dollars spent by the candidates — not to mention outside groups — Tennessee's midterm elections are here.

Early voting began Wednesday, Oct. 17, to determine Tennessee's next governor, U.S. senator, congressional representatives and dozens of state lawmakers, with the potential to alter the makeup of both state and federal legislative chambers.

From Oct. 17 through Nov. 1, Tennesseans can cast their ballots early in the Nov. 6 election.

Here's what you need to know if you plan to vote in the midterm.

Who is on the ballot for Tennessee governor?

Term-limited Gov. Bill Haslam, a Republican first elected to the office in 2010, cannot seek a third term.

Williamson County businessman Bill Lee, the Republican nominee, is facing former Nashville mayor Karl Dean, the Democratic nominee, in the race to replace Haslam.

The race has become the most expensive in state history, costing more than $62.5 million, according to the latest campaign finance disclosures. The figure does not include outside spending in the race.

Lee has spent $2.1 million since the primary, while Dean has spent $3.3 million.

In addition to the two parties' nominees, 26 independent candidates will appear on the ballot.

Who is on the ballot for U.S. Senate?

After announcing in September 2017 he would not seek re-election, U.S. Sen. Bob Corker, R-Tenn., confirmed in February he was retiring from the position and would not seek a third term.

U.S. Rep. Marsha Blackburn, the Republican nominee, and former Tennessee Gov. Phil Bredesen, the Democrat in the race, have also engaged in the most expensive U.S. Senate race in the state's history, spending more than $50 million.

Independent groups have spent more than $30 million in Tennessee this election season, according to recent filings with the Federal Election Commission.

Besides Bredesen and Blackburn, six independent candidates are on the ballot.

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Is it too late to register to vote?

Yes. The registration deadline for the Nov. 6 election was Oct. 9. To check your registration status, visit govotetn.com.

Where do I go to vote early?

In addition to the voter's county election commission office, satellite voting locations are set up by the county's election commission until five days before the election.

The early voting sites are open Monday through Saturdays and some evenings. Each county election commission sets their own hours and locations for early voting.

To find out your early voting options, check your local election commission's website or download the GoVoteTN app.

Do I need to bring a photo ID to vote in Tennessee?

Yes. Voters in Tennessee must bring a valid photo identification card, which can include a driver's license or photo ID issued by the state of Tennessee, a U.S. passport, a U.S. military photo ID or a Tennessee handgun carry permit that includes a photo.

College student IDs, city or county-issued IDs and out-of-state photo IDs are not accepted.

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Reach Natalie Allison at nallison@tennessean.com. Follow her on Twitter at @natalie_allison.