The invasive emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is an Asian beetle that feeds on ash (Fraxinus spp.) trees. Emerald ash borer was discovered in southeastern Michigan in 2002 and has subsequently been found to be responsible for the death or decline of over 15 million ash trees. We used tree ring analyses to examine the historical dispersal patterns and spread of emerald ash borer over a geographic area encompassing the known core infestation in southeastern Michigan. Increment core samples from emerald ash borer-killed ash trees were preferentially collected over declining or non-stressed ash trees on at least a 3.0 × 3.0 mile sampling grid throughout the region. Crossdating and other dendrochronological analyses are in progress that will reveal when and where emerald ash borer initially became established in southeastern Michigan and how it spread historically.