Problem, Research Strategy, and Findings: Planners increasingly involve stakeholders in co-producing vital planning information by crowdsourcing data using online map-based commenting platforms. Few studies, however, investigate the role and impact of such online platforms on planning outcomes. We evaluate the impact of participant input via a public participation geographic information system, PPGIS, a platform to suggest placement of new bike share stations in New York City and Chicago. We conducted two analyses to evaluate how close planners built new bike share stations to those suggested on PPGIS platforms. Our proximity analysis found that only a small percent of built stations were within 100 ft (30 m) of suggested stations, but our geospatial analysis showed a substantial clustering of suggested and built stations in both cities, not likely due to random distribution. We find that the PPGIS platforms have great promise for creating genuine co-production of planning knowledge and insights and that system planners did take account of the suggestions offered online. We did not, however, interview planners in either system, and both cities may be atypical as is bike share planning; moreover, multiple factors influence where bike stations can be located so that not all suggested stations could be built.Takeaway for Practice: Planners can use PPGIS and similar platforms to help stakeholders learn by doing and to increase their own local knowledge to improve planning outcomes. Planners should work to develop better online participatory systems and to allow stakeholders to provide more and better data, continuing to evaluate PPGIS efforts in order to improve the transparency and legitimacy of online public involvement processes. Keywords bike share; PPGIS; crowdsourcing; co-production Public participation is a critical element in most formal US planning processes. The American Institute of Certified Planners' Code of Ethics and Professional Conduct specifies that planners must "give people the opportunity to have a meaningful impact on the development of plans and programs that may affect them" (AICP, 2016). Planners now widely include digital participation methods in their practice, intensifying questions about the efficacy and legitimacy of citizen input. We assess evidence on how planners use crowdsourcing as a form of