Polls opened at 6 a.m. Tuesday morning, and will remain open until 7 p.m. for voters to cast a ballot in several races. 

KJZZ's Nick Blumberg spent some time at a polling location in Tempe, the Arizona Historical Society Museum. He checked in over the course of the morning with Morning Edition host Dennis Lambert. Here are some of the highlights:

Voters trickled in slowly over the course of the morning. In-person voting is increasingly being displaced by early voting -- nearly half of Maricopa County voters are on the permanent early voting list.

According to the county elections department, they had 745,259 requests for an early ballot. As of Monday afternoon, 344,676 had been returned -- about 46 percent.

There are 724 polling locations in Maricopa County, down from a previous high of 1,142. As early voting has become more prevalent, the county combined neighboring precincts and says they've saved about a million dollars in doing so.

The county has about 4,300 people working at polling locations.

Anyone who hasn't mailed in an early ballot can drop it off in person at any polling location -- just make sure to sign the envelope.