Dengue viruses circulate between mosquito vectors and humans, causing an estimated 100-million dengue infections annually. In the last decade, the Americas have experienced a dramatic increase in severe disease cases (dengue hemorrhagic fever), with devastating public health consequences. Of particular concern is the potential for the expansion of intense dengue virus transmission into cooler, high altitude cities that are presently outside of transmission zones but may be at risk under scenarios of climate change, such as Mexico City. To address this problem we are employing a coupled natural and human systems approach to explore the ecology of Aedes (Ae). aegypti, the mosquito vector of dengue, in Mexico. A field study is being conducted along a transect from Veracruz City to Puebla City, ranging from relatively warm and wet low-elevation coastal environments with well established vector mosquito populations and intense dengue virus transmission, to comparatively cool and dry high-elevation mountainous areas which currently are free of the mosquito vector and local virus transmission. Along the transect we are measuring how climatic, socio-economic and infrastructure factors are coupled with Ae. aegypti abundance. These data will be synthesized into a spatially predictive model to examine if, how, and why the range of the dengue vector Ae aegypti may change in the future. Early results from our first field season will be discussed in this presentation.