Final answer:
State legislatures are generally responsible for drawing congressional districts every ten years, a process called redistricting, after the U.S. Census data is collected. However, this process can lead to gerrymandering, prompting some states to form independent commissions to tackle redistricting more fairly.
Step-by-step explanation:
The responsibility for drawing congressional districts every ten years, an undertaking known as redistricting, typically falls to the individual state legislatures. This is done following the collection and analysis of population data by the U.S. Census. Adjusting the boundaries of these districts is essential to ensure equal representation in Congress, as populations within states can increase or decrease over time. While states are allotted a certain number of representatives, the process of drawing district boundaries can be controversial, particularly when it results in gerrymandering, where lines are drawn to favor a specific political party or to diminish the influence of certain demographic groups. Some states have countered this by establishing independent commissions to oversee the redistricting process, to attempt to create fair and competitive electoral districts.