Redistricting is the redrawing of a state’s legislative and congressional districts. The U.S. Constitution requires that all states redraw their maps every 10 years following the U.S. Census so that districts are of nearly equal population. States gain and lose population, which affects the number of congressional representatives each state has. And also populations shift within states, changing the size of both the congressional and state legislative districts.
To learn more about redistricting go to…
Redistricting 101 - All About Redistricting
10 Things You Should Know About Redistricting
Redistricting in the United States - Wiki
LWVUS’ Nation-wide People Powered Fair Maps Project