The late 1940s and early 1950s saw a consolidation of nuclear data production as a central research program, with systematic measurements of neutron interactions and the development of practical neutron sources shaping reactor design and shielding calculations. Researchers increasingly relied on simple, transferable parameterizations of scattering and cross sections, enabling cross-nucleus comparisons and broad applicability. A data-centric approach emerged, unifying experimental results with minimal-theory fits and setting the stage for standardized nuclear data libraries used in engineering and safety analyses.