Pacific razor clam shell growth was examined using data provided by the Alaska Department of Fish and Game containing 235,606 length-at-age records based on visible annuli on the shell from 57,534 individual clams measured from 1966 to 2021 at nine locations in Cook Inlet, AK. Shell growth was modeled via the von Bertalanffy Growth Function treating each individual clam as a random effect. Asymptotic mean length at time infinity (L_∞) varied considerably between sites, from 121.35 to 186.58 mm, as did the growth coefficient k which ranged from 0.28 to 0.54 y^–1. When both L_∞ and k were examined collectively via a growth performance index (∅′), all Cook Inlet sites were similar (∅′ range: 3.80–4.02). The growth performance of Pacific razor clams in Cook Inlet was also compared with summary statistics from previously published mean length-at-age estimates for Pacific razor clams across their distribution. Growth performance estimates from Alaska and British Columbia sites were largely similar, whereas sites in Washington, Oregon, and California were generally characterized by faster growth and smaller maximal lengths. Although this study did not attempt to quantitatively identify predictors of variation in growth parameters and performance within and outside of Cook Inlet, AK, this manuscript concludes with speculations on possible correlates to growth and recommendations for future work.