Voting districts in the United States are very poorly designed if our goal is to promote democratic elections and representative officials. Our country has one of the higher incumbency rates in the world and a significant factor in this is the design of our voting districts. For one of the most ludicrous example, examine district four in Chicago.
These districts are formed or changed by current officials and often skew any future elections in the incumbent's favor, decreasing competition. As any economist will tell you, competition induces an efficient market, and this concept similarly applies to the "market" for politicians.
The creation of uniform voting districts or an independent body to design voting districts, will aid in the election of relatively more competent officials.