Citizen science can engage the public with nature while also accelerating the rate of data collection, which is critical to track the rapid pace of modern environmental change. Camera traps are ideal tools for citizen science because their photographs can be verified by experts, and the unique animal pictures provide an enjoyable experience for volunteers. Although not a replacement for traditional museum collections, these archives of photo-vouchers can be accumulated faster, over larger areas, and are noninvasive. Through the eMammal project, we have developed field protocols, training modules, education materials, and the cyberinfrastructure to enable large citizen science camera trapping programs. We have worked with volunteers and scientists in 11 states to monitor over 11,000 sites on public and private land, recording 0.5 million detections in >700 camera-years of monitoring effort. These data have been used in peer review publications on invasive species, predator-prey relationships, population monitoring, and the impact of recreation on wildlife. We are now scaling up to work with citizens to run camera traps at 20,000+ sites across the state of North Carolina. Internationally, we are working with over 50 schools in four countries, documenting endangered species living on community land. The eMammal data management framework has also been useful for non-citizen programs, including surveys by governments and academics, contributing to a growing camera trap archive at the Smithsonian. Volunteers consistently report positive experiences from camera trapping, and surveys show they increase their knowledge and become stronger advocates for conservation by running camera traps.