Trees planted along highway roadsides have the potential to provide many benefits, including managing stormwater, buffering adjacent communities from the highway, and providing wildlife habitat and corridors. Trees need to grow to maturity to meaningfully perform many of these functions and make investments in their planting worthwhile. Yet little is known about factors that can affect the longevity of trees in highway settings. In 2018 we conducted a re-inventory of over 3,000 trees from three tree planting projects along a highway in northern Illinois to evaluate multi-decade survival in this setting for trees planted in 1988, 1997, and 2008. We also examined the effects of species’ environmental tolerances and site location factors on survival. We observed 27% and 30% survival of trees in the 1988 and 1997 planting cohorts while the 2008 planting cohort survival was 87%. About 6% of trees in the re-inventory appear to have been removed because of construction activities based on a review of historic aerial photos. Species with greater drought tolerance were more likely to be alive, likely reflecting both the climate of northern Illinois as well as potential stressors such as poor soil conditions. Trees planted on steeper slopes were also less likely to be alive. These results highlight the importance of species choice and site selection for highway tree planting projects. As highways can be subject to frequent cycles of construction and infrastructure replacement, it is particularly crucial to locate trees in locations with a low likelihood of future construction in order to increase long term survival and the provision of benefits.