The United States National Harmful Algal Bloom Observing Network (NHABON) brings together local, state, Tribal, regional and federal HAB observing capabilities to enable forecasting and early warning systems for harmful algal blooms that leverage economies of scale to provide sustained and reliable information needed to protect public health and food safety. NHABON is a multi-agency partnership that leverages decades of investment in the regional ocean observing systems forming the backbone of the NOAA Integrated Ocean Observing System.In this presentation, I will discuss the emerging NHABON Community of Practice in the U.S., a regional alliance of the Global Ocean Observing System (GOOS), designed to unify early warning systems into a cohesive national network. Specifically, I will review development of the HAB Data Assembly Center: a centralized location for accessing HAB data products, cyberinfrastructure for processing near real-time plankton imagery and biotoxin data, a common code repository for machine learning models and training data sets, and data science and data management support for research teams issuing critical food safety alerts. I will provide examples of how regional systems in the U.S. can be coordinated through a national network, support technologies and monitoring programs to detect blooms, distribute forecasts and early warnings, and provide data and information products. The ultimate aim of NHABON is global access to sustained service delivery for operators and managers in aquaculture, fisheries, and public health.