The deadline to register to vote in the upcoming primary election is just days away, and already more Collin County residents are eligible to participate compared with 2016.

As of Jan. 29, roughly 600,253 Collin County residents are registered to vote, according to the county office. A total of 501,224 were registered in 2016.

The March 3 primary election will determine which candidates will appear on the general election ballot in November. This year’s primary pits incumbent Republican President Donald J. Trump against a slew of Democratic candidates. Several Republican candidates have also stepped up to challenge Trump.

Also included in the election are candidates for the House of Representatives at both the federal and state level, as well the US Senate. Registered voters in Collin County can also vote in the races for Texas Railroad Commissioner, tax assessor-collector, Precinct 1 and 3 commissioners, and district judges.

Voter turnout in primaries is typically lower than during general elections. During the 2016 primary, roughly 31% of registered voters in Collin County turned out to vote.

The number of registered voters in Collin County increased by 38,860 people between the primary election and the general election in 2016. Turnout also increased, with roughly 68% of registered voters showing up to vote in November.

Those who wish to cast ballots in the primary must register to vote by Feb. 3. In Texas, a registered voter is not required to affiliate with a particular party before voting in that party’s primary election, according to the Texas secretary of state’s office.

However, once a voter has voted in a particular party’s primary, they cannot vote in the opposite party’s runoff election. Party affiliations automatically expire at the end of each calendar year, according to the secretary of state’s office.

Collin County residents can check their registration status by visiting this site. For more information on party affiliation rules, click here. For frequently asked questions about the March 3 primary, click here. Sample ballots with a complete list of candidates are available on the Collin County elections page.

Those that are eligible for early voting from Feb. 18-28 can find more information on polling locations here.

Editor's note: This story has been updated to include more information on Collin County elections.