On Saturday, September 20th, New Zealand held its 51st general election, in which the center-right National Party and its leader, Prime Minister John Key, made some modest gains. If this all sounds rather dull — a country of less than 5 million people having an election in which no power changes hands — that's fair enough. But it's worth paying attention, as New Zealand's parliament is better designed than just about any other developed country government.The world's best electoral systemIf you pay any attention at all to American politics, you know that Republicans have a healthy majority in the House of Representatives, with 233 seats (53.6 percent) to Democrats' 199 (45.7 percent; three seats are vacant). So it'd be reasonable to expect that in the most recent election, 2012, they won the popular vote by a similar margin.They did not. In fact, House Republicans lost the popular vote, with 47.6 percent to Democrats' 48.8 percent. This isn't a particularly common occurrence, but it does happen from time to time; in 1996, Democrats also won the popular vote for the House while not gaining a majority or plurality of seats.The standard explanation for why this kind of thing happens is that Democratic House districts tend to be more Democratic, on average, than Republican districts are Republican. That means that Democratic votes are \wasted\ running up the margins in safe districts, whereas Republican votes are spread out enough to garner more seats-per-vote. Reasonable people can differ over the extent to which this pattern is explained by gerrymandering or the fact that Democrats tend to naturally cluster together geographically (I'd argue that a fair districting system would take the latter into account but that's another matter).But the fact that it leads to obvious injustices is hard to deny. It's not fair to Democrats living in rural Texas, or Republicans living in Manhattan that they will almost certainly never be represented by someone with their political views. It's not fair to Democrats and Republicans living in their own parties' safe districts that their votes count for less than if they lived in swing districts. It's not fair to those in swing districts who lose narrowly; if, say, a Democrat wins a seat 51 percent to 49, that means roughly half the district isn't seeing their interests represented.This is not an inevitable feature of the political system, and as Reihan Salam noted in Slate a few weeks back, most other countries have devised a solution: proportional representation. There are a bunch of different ways to do this. One is creating multi-member districts, and then having voters rank candidates through a process known as single transferable vote (STV); this is what Rob Richie and the team at FairVote, the main US lobbying group on this question, advocate. The simplest system would be pure party-list representation, as practiced in the Netherlands and Israel, in which there are no districts, voters choose parties rather than candidates, and parties get roughly the same percentage of seats as they did votes; a milder version, as used in Spain and Norway, does this at the district level.Either of these would be huge improvements over the US status quo. But neither is ideal. Single transferable vote systems are party-agnostic and can't ensure that parties are represented in proportion to the votes they received as well as a party-list system can. But pure party-list systems can lead to a destabilizing proliferation of small parties which are able to extract promises from the bigger parties in exchange for joining their coalitions.Party-list systems make it hard for a single party to get a majority, which means that if, say, a party has 45 seats out of 100, it still needs to win over a party with 6 seats to govern. The 6 seat party then has significant power to demand stuff, out of proportion to its actual level of support. So ironically, this form of proportional representation can have patently undemocratic consequences. Stuff like this has happened frequently in Israel, with fairly deleterious results.The best proportional representation (PR) system, then, is a twist on party-list voting known as mixed-member PR, or MMP for short. MMP has voters select both a candidate in their local district and a party they'd like to win a majority. Everyone who wins a district gets a seat, and then additional seats are given out to ensure that parties are represented in proportion to their share of the party vote. This has a number of advantages. Unlike party list representation, people still have representatives with at least some ties to their area, for whatever that's worth.new zealand ballotBut more importantly, it means parties have to be organized enough to compete in a decent number of districts in order to have a shot. That discourages the kind of excessive party formation that happens under pure party-list representation, while still ensuring that smaller parties get some say.Germany and New Zealand both use MMP, and the result in each case is a slightly altered version of a two-party system. It's rare for the major parties in either country to get an outright majority (though it appears the National Party might in New Zealand), but typically they have enough ideological allies in smaller parties to form a government nonetheless. Germany also has a tradition of grand coalitions between its two main parties, but New Zealand shows the system can work even when there isn't that kind of bipartisan collaboration (as, let's be honest, there wouldn't be in a hypothetical United States with MMP). Neither country has faced problems with government formation of the kind nations using purer party list systems often do. Just recently New Zealand held a nonbinding referendum on its voting system, and voters opted to stay with MMP by a wide margin.It's worth emphasizing how rare MMP is: only four countries (Germany, New Zealand, Lesotho, and Romania) use it. And none of the other three can claim New Zealand's other big advantage…UnicameralismThe worst thing about the United States Senate — besides its history as a bulwark for slavery and white supremacy, its flagrant violation of the principle of \one person