The US has long been the world’s innovation powerhouse, based on a system that combines public funding with private initiative. Yet this model is under strain. Using newly digitised US patent data since 1950, this column shows that publicly funded but privately owned patents – just 2% of all US patents – account for around 20% of medium-term fluctuations in productivity and GDP growth. As funding cuts threaten the most productive funders of public R&D, the authors argue that America’s