Describe how single member districts discourage minor parties

The existence of single-member districts discourages the creation of minor parties because the party that receives the most votes secures the office. In other words, the winner gets everything, and other parties have nothing to show for their efforts. If, by way of illustration, the Green Party fielded candidates in all 435 House races and received 20 percent of the vote in each district, it would not win any seats at all. In a system with proportional representation, seats in the legislature are allocated according to the party's share of the popular vote. Thus, minor parties are rewarded for fielding candidates in elections because their efforts result in at least a modicum of representation in the legislative branch.