Pollinators, such as bees and other insects, are essential to ecosystems and agriculture, yet their populations are in decline. Understanding why this is happening, and how we can help, requires long-term data on their interactions with plants. However, historical records of these relationships are rare. The research team has uncovered a unique dataset from over 50 years ago, documenting thousands of plant-pollinator interactions across California, from coastal regions to mountain peaks. By revisiting these locations and comparing past and present data, the team will investigate how pollinator communities have changed over time and which species are most at risk. This study is the first to examine multiple locations, providing critical insights into how long-term environmental change reshapes communities. By making data publicly available and collaborating with community scientists, the research will help ensure ongoing monitoring of pollinators in California. The study will also provide hands-on learning experiences for students and volunteers, fostering the next generation of environmental scientists. Given California’s role as a global bee biodiversity hotspot and key pollinator-dependent agricultural area, the insights gained from this research will have far-reaching implications for pollinator conservation and food security. The research will provide the first multi-site, longitudinal study of the interacting effects of environmental change stressors on plant-pollinator