How are elections affected by the votes of people living abroad? The majority of states now allow extra-territorial voting in some form, but the research literature on this topic remains underdeveloped. Moreover, even though extra-territorial voting raises issues about the relationship between territory and political obligation that are relevant to political geographers, political geography has been under-represented in discussions on the topic. Against this background, this research examines a century of overseas voting impacts in New Zealand, a country with an unusually long recorded history of such activity. The study identifies three types of extra-territorial voting impact over the period 1914-2011, referred to as swings, interregnums and feedback effects.