Domestically funded (and performed) research and development (R&D) has historically been a major source of productivity gains in U.S. agriculture, and a principal source of R&D spillovers to the rest of the world. In the waning decades of the 20th century, U.S. policymakers opted to ratchet down the rate of growth in public support for food and agricultural R&D. As the 21st century unfolds, slowing growth gave way to real cutbacks, reversing the accumulation of U.S.- sourced public R&D capital over most of the previous century and more. The 2014 Farm Bill did little to reverse these long-run research funding trajectories—politicians apparently ignored economic evidence about the still substantial social payoffs to that research and the consequent slowdown in U.S. agricultural productivity growth associated with the spending slowdown. Meanwhile, R&D spending by other countries has been moving in different directions. We present new evidence that today’s middle-income countries—notably China, Brazil and India— are not only growing in relative importance as producers of agricultural innovations through investments in public R&D, they are also gaining considerable ground in terms of their share of privately performed research of relevance for agriculture. The changes in global public and private R&D investment trajectories are accelerating of late, and substantive. If history is any guide to the future, these changing R&D trajectories could have profound consequences for the competiveness of U.S. agriculture in the decades ahead.