California's congressional districts

California is the most populous U.S. state and as a result has the most representation in the United States House of Representatives, with 53 Representatives. Each Representative represents one congressional district.

The 1990 census gave California seven additional congressional seats. Attempts by the legislature to draw up new districts were unsuccessful, as three different plans drawn up by the Democratic-controlled Legislature were vetoed by Republican governor Pete Wilson. In September 1991 the California Supreme Court took jurisdiction over the redistricting process to break the stalemate. Districts were drawn up by a panel of retired judges.

After the 2000 census, the California State Legislature was obliged to complete redistricting for House of Representatives districts (in accordance with Article 1, Section 4 of the United States Constitution) as well as California State Assembly and California State Senate districts. It was mutually decided by legislators that the status quo in terms of balance of power would be preserved - a so-called Incumbent Protection Plan. A bipartisan redistricting effort was done, and districts were configured in such a way that they were dominated by one or the other party, with few districts that could be considered competitive. In some cases this resulted in extremely convoluted boundary lines.

In the 2004 elections, a win by less than 55 percent of the vote was quite rare. This was seen in only five out of 80 State Assembly seats and two out of 20 State Senate seats up for election. The congressional seats were even less competitive than the state legislative districts - just three of the 53 districts were won with less than 60 percent majority in 2004.

...
Wikipedia