1. Japan's new electoral system:
2. This assumption does not take into account the argument that the municipal mergers not only reduced foot soldiers long central to the LDP as a party organization, but also disproportionately reduced support for the LDP as the party in power in areas where municipal mergers cost people their jobs and positions. However, any potential bias in the results works in favor of the argument put forth by overestimating the amount of LDP support after the mergers.
3. Municipal mergers in Japan have a long history, beginning in the 1870s in the Meiji era, but the most recent round of mergers, the so-called Grand Mergers of the Heisei Era (Heisei no dai gappei), began in earnest in 1995 with the passing of the General Decentralization Law (chihou bunken ikkatsu hou). In the forty-first lower house elections in 1996, all three major parties, including the LDP and the DPJ, included municipal mergers in their party manifestos.
4. Mergers conducted in this period are considered part of a nationwide movement called Heisei no dai gappei.
5. Electoral Reform and the Fate of Factions: The Case of Japan's Liberal Democratic Party