As of May 10th, 2016, more than 75% of states have held either presidential primaries or caucuses. FairVote has compiled the number of votes casts in state primaries for each candidate to this point, as well as the reported number of votes in state caucuses--though caucus numbers are less reliable than primary elections. Here is summary analysis of state presidential primary election voter turnout to this point in the nomination process.

Primary Turnout in 2016 Compared to Contests in 2008 and 2012

• Nationwide presidential primary turnout remains low: While some individual states have posted record turnout for one or the other major party, turnout among eligible voters in this year’s presidential primary season still remains objectively low. At this point in the process, 30.14% -- less than one-third of eligible voters -- have participated in a primary contest. The last time both parties had competitive presidential nomination races was 2008, which saw 30.82% voter turnout after all states had participated.

• Republican Turnout Steadily Increases in Wisconsin: Wisconsin garnered one of the highest turnout percentages in states voting so far, with about 49% of all eligible voters casting a ballot. A closer look at the Republican contest reveals a steep increase in turnout between 2008, 2012, and 2016. While only410,607 Republican voters participated in the state’s primary in 2008, that number increased to 787,847 in 2012. This year, Republican turnout surged to 1,100,834, representing 25.71% of the voting eligible population in that state. Wisconsin Republicans voted on April 4th, when only Ted Cruz, Donald Trump, and John Kasich remained in the race, though many candidates who had already dropped out still appeared on the ballot.

• Democratic Turnout Dips in Vermont: Vermont, another state with consistently high percentages of voter eligible population turnout, saw a slight dip in Democratic primary participation compared to 2008. The last time Vermont Democratic primary voters faced an open field in 2008, 155,279 participated in the primary, about 32% of the voting eligible population at the time. This year, only about 27% of the voting eligible population cast a vote in the Democratic contest, representing 134,600 votes, or a drop of around 20,000 votes. Of course, Vermont maintains open primaries, so it is possible that some voters who chose to vote in the Democratic contest in 2008, instead chose to participate in the Republican contest in 2016. Republican turnout in Vermont increased from 40,120 in 2008 to 61,038 in 2016.

• Republican Turnout Doubles in Louisiana, Overall Turnout Stagnates: Louisiana, which has one of the lowest turnout primaries based on voting eligible population so far this year, nonetheless nearly doubled their primary participation in the 2016 Republican contest compared to 2008. The closed primary state saw 161,169 Republicans cast primary ballots in 2008, and 186,410 in 2012. In 2016, however,301,241 Republicans voted, representing 9.24% of the voting eligible population and almost doubling the participation rate in 2008. Louisiana’s overall voting eligible participation rate did not significantly increase, climbing only to 18.17% in 2016 from 17.7% in 2008.

• Moderate Participation Gains for Republicans and Democrats in Connecticut: The overall participation rate of the voting eligible population in Connecticut has also remained relatively stable compared to 2008, increasing only about half a percentage point from 20.5 in 2008 to 20.99 in 2016. Republicans in the state, however, saw about 61,000 new voters in their primary contest this year compared to 2008. In 2016, 213,212 Republicans cast a vote in Connecticut as opposed to only 151,605 in 2008. Both are substantially higher than the participation rate in 2012 Republican Primary, which garnered only 2.3% of the voting eligible population with 59,639 votes.

Highest and Lowest Turnout Among Primary States

Of all of the states that have conducted a presidential primary election thus far, New Hampshire’s first-in-the-nation primary boasts the highest turnout with 52.02% of the state’s voting eligible population casting a vote. The fact that the state played host to a crowded field of candidates each running aggressive campaigns on the ground, combined with the fact that it is a particularly small state likely played a role.

Of the top five states in primary voter turnout, all five have either an open or semi-open primary system. Wisconsin, Vermont, and Illinois each have an open primary system, in which any registered voter can vote in either party's primary regardless of whether they are affiliated with a political party. Vermont and Massachusetts have a “semi-open” system, which also allows non-affiliated voters to cast a vote for whichever party they choose, however those affiliated with a party can only vote in that party's primary.

Of the five states with the lowest presidential primary turnout to date, all took place after March 1st--also known as “Super Tuesday”--at which point the Republican field of candidates had been significantly winnowed down. In addition, four of the five states have a closed primary system, in which voters that are not affiliated with a political party are unable to cast a vote.

FairVote has compiled a comprehensive spreadsheet which highlights state-by-state popular vote totals for every presidential candidate through May 3rd, 2016. Based on these numbers, we’ve also done analysis on vote totals received by presumptive nominees Donald Trump and Hillary Clinton. Stay tuned for more presidential primary season voter turnout analysis based on the above spreadsheet.

Editor's note: This article, written by Molly Rockett and Austin Plier, originally published on FairVote's blog and has been modified slightly for publication on IVN.