7-Eleven will open voting in its fifth quadrennial 7-Election Presidential Coffee Cup Poll on Sept. 6, taking the political pulse of America’s coffee consumers through Election Day, Nov. 8.

Yeah, it’s unofficial and totally unscientific, but the giant convenience store chain says in each of the presidential elections since 2000, the votes cast by coffee drinkers choosing a red cup if they lean toward the Republican nominee and blue if they lean Democrat has mirrored real voting.

The political waters are a little murky for some voters this year, so 7-Eleven has added a ballot option for undecideds, the purple “Speak Up” cup. This cup is intended to give people not interested in taking sides a voice a chance to “write in” their candidate or important issue on the back of the cup.

“While preparing for the 2016 count-the-cups poll, we learned that voters, particularly younger ones, aren’t just talking about candidates or even political parties this election. They’re taking to social media to talk about a variety of issues that are important to them,” 7-Eleven’s marketing vice president Laura Gordon said in a news release. “So we added the third ‘Speak Out’ cup to let people say what’s on their mind, whether checking one of the boxes on the back of the cup or writing one in and sharing it” on social media with the hashtag #7ELECTION.

The company estimates more than 1 million people buy a cup of coffee at a 7-Eleven store each day. The polling will be instantly tabulated as purchases are made. National, state and major-city results will be posted daily at 7election.com.