Republican incumbent John Duarte and Democrat Adam Gray are facing off for the second time.
Two years ago, Gray lost to Duarte by only 564 votes.
Duarte says his campaign has given it their all leading up to Tuesday, with ads and door knocking.
He says he's known all along how important winning this seat was to control the house.
Gray has spent a lot of the campaign saying he is the more moderate candidate in this race.
He has racked up some endorsements from prominent republicans in this district, including Merced County Sheriff Vern Warnke.
A lot of money was raised and spent on this campaign, which is one that is gaining national attention.
Democrats are looking to regain control of the House of Representatives, and the 13th congressional seat could be one of the four needed seats.
The 13th district, which was redrawn following the 2020 census, now includes parts of Fresno, Madera, Merced, San Joaquin and Stanislaus counties.