本文由歷年來台灣地方選舉各主要政黨，得票、席次比率的消長，以及藍、綠兩大陣營，歷年來各縣市縣市長選舉得票消長，分析政治版圖與選舉制度，對於2005年縣市長選舉政治勢力消長所造成的影響。本文認為一般印象當中所謂的民進黨於2005年縣市長選舉大敗的理解，僅是單純就民進黨於縣市首長席次佔有比率的大幅下挫，進而加以論斷實有其不足。民進黨之所以在2005年縣市首長選舉，出現席次佔有率大幅下挫的現象，除了是單一席次選舉的效應之外，更可以說反映出泛藍整合成功的條件下，泛綠的選票成長區集中在南台灣，進一步強化了北藍南綠的政治格局。

On December 3rd 2005, "three-in-one" elections were held in Taiwan. The Kuomintang (KMT) won 14 out of 23 contested county magistrate and city mayor seats, while the Democratic Progressive Party (DPP) garnered only 6 seats: a loss of 4. However, there was no significant shift in the demarcation between pan-green and pan-blue votes. The DPP received 42% of total votes, a 3.3% decrease from the previous election, versus the KMT's 51 %. The key to the gap between the number of seats and votes was the "single-member district system." The results of the recent election have implications for the legislative election in 2007, because the "single­member district system" tends to have a disproportionate effect on political parties by marginalizing the political space of smaller parties.