"The census, apportionment, and redistricting are interrelated activities that affect representation in the U.S. House of Representatives. Congressional apportionment (or reapportionment) is the process of dividing seats for the House among the 50 states following the decennial census. Redistricting refers to the process that follows, in which states create new congressional districts or redraw existing district boundaries to adjust for population changes and/or changes in the number of House seats for the state. [While the federally conducted census informs apportionment, there is no federal legislation outlining how House seats should be allocated within each state. Therefore, redistricting is governed largely by state laws and party politics with some federal oversight due to historic repression of marginalized peoples' voting rights.] At times, Congress has passed or considered legislation addressing apportionment and redistricting processes under its broad authority to make law affecting House elections under Article I, Section 4, of the U.S. Constitution. These processes are all rooted in provisions in Article I, Section 2 (as amended by Section 2 of the Fourteenth Amendment)." Sarah J. Eckman, Apportionment and Redistricting Process for the U.S. House of Representatives, Congressional Research Service (2019).
Gerrymandering: The practice of dividing or arranging a territorial unit into election districts in a way that gives one political party an unfair advantage in election (from Merriam-Webster Dictionary.
Ballotpedia - explains that gerrymandering has its roots in the early days of U.S. and was coined by the Boston Globe when describing the new state senate district map in 1812 approved by Massachusetts Gov. Elbridge Gerry. The Globe said the new district appeared like a salamander.