A recently discovered, small, and disjunct population of Quercus cedrosensis just north of the US border with Mexico faces a barrage of threats from wildfires, drought, and succumbing to bulldozer blades during border-wall construction. Recognizing the immediacy of the need to preserve these plants, especially given the lack of any ex-situ conservation accessions from the US, the San Diego Botanic Garden (SDBG) designed a robust conservation project in collaboration with more than a dozen partners including other botanical gardens, federal, state, and municipal agencies, the Global Conservation Consortium for Oak, and the Center for Plant Conservation to work toward preserving this little-known species. In 2021, SDBG completed a comprehensive survey of the rugged US range of this species in addition to visiting occurrences in northern Baja California. Working with a diverse team of partners, SDBG and colleagues managed to develop and distribute the first ex-situ conservation accessions from Q. cedrosensis in the US using methods including acorn propagation, rooting of traditional cuttings, tissue culture propagation, and air layering. SDBG is proud to be growing and studying the first plants of this species associated with specific maternal and clonal lines from the wild US population, but the Garden is also dedicated to continued development of additional partnerships, expertise, and other resources necessary to lead collaborative conservation and research efforts related to Q. cedrosensis and other threatened oak species from the Southwestern US and northern Mexico for decades to come. [ABSTRACT FROM AUTHOR]