Reply #15: Sorry, but with single-seat districts, you will likely never see a viable third party in the US [View All]

[Selatius]

A two-party system often develops spontaneously from the single-member district plurality voting system (SMDP), in which legislative seats are awarded to the candidate with the most total votes within his or her constituency, rather than apportioning seats to each party based on the total votes gained in the entire set of constituencies. This trend develops out of the inherent qualities of the SMDP system that discourage the development of third parties and reward the two major parties.

The most obvious inhibiting feature unique to the SMDP voting system is purely statistical. A small third party cannot gain legislative power if it is based in a populous area. Similarly, a statistically significant third party can be too geographically scattered to muster enough votes to win seats, although technically its numbers would be sufficient to overtake a major party in an urban zone. Gerrymandering is sometimes used to counteract such geographic difficulties in local politics, but is impractical and controversial on a large scale. These numerical disadvantages can create an artificial limit on the level at which a third party can engage in the political process

http://en.wikipedia.org/wiki/Duverger%27s_law

If you want more than two parties operating simultaneously in the House, then you should reward seats according to proportional representation and junk congressional districting, which lends itself to gerrymandering.