Texas—along with Montana, Nevada and North Dakota—are the only U.S. states that have biennial legislatures, whereas other states meet annually, according to the National Conference of State Legislatures, a nongovernmental analysis organization.

The Texas Legislature, which convened Jan. 8, has been meeting every two years since it was established in 1845.

According to The Texas Tribune, it was difficult to traverse the state during the 19th century, which is why lawmakers set biennial meetings in the Texas Constitution from the beginning.

According to the Texas House of Representatives website, the maximum duration of a regular session is 140 days. However, the constitution gives the governor power to call as many special sessions as they want. Special sessions are limited to 30 days, during which the Legislature is permitted to pass laws only on subjects submitted by Gov. Greg Abbott.