<p>Studying coastal ecogeomorphic change relies on reliably and accurately dating recent sediment deposits. While a handful of short-lived radioisotopes are proven suitable geochronometers, all have limitations. One particularly useful anthropogenic radionuclide, ¹³⁷Cs, is rapidly approaching extinction due to its half-life. We evaluate whether the bomb-produced radionuclide ²⁴¹Am is a reliable alternative to ¹³⁷Cs. In 75 cores from eight Oregon intertidal zones, ²⁴¹Am was readily detectable in higher-elevation marsh sediments and, when present, was less mobile post-deposition than ¹³⁷Cs. Accretion derived from the depth of the ²⁴¹Am and ¹³⁷Cs peaks associated with the height of nuclear proliferation were statistically similar to rates determined from excess ²¹⁰Pb. Although ²⁴¹Am activities are relatively low in these environments, their detectability is expected to increase as ²⁴¹Pu continues to decay. ²⁴¹Am may therefore be an accurate event-horizon chronometer in high marsh sediments, and will likely become an increasingly preferable dating technique compared to ¹³⁷Cs geochronology.</p>