Conversion exemplifies one of the most productive word-formation processes in English. Yet how this phenomenon has evolved over time and what factors drive its development remain underexplored. This study investigates changes in noun-to-verb conversion degree and the semantic, morpho-phonological, stylistic and frequency-based factors shaping this process. Using data from the Corpus of Historical American English, we analyzed 637 noun-to-verb conversion pairs from the 1920s to the 2010s and modeled their trajectories with generalized linear mixed effects models. Results reveal a significant increase in conversion degree over time. This reflects a reconfiguration of how efficient communication is achieved, whereby categorical information is increasingly conveyed by context rather than overt morphological marking. We further found that nouns with higher semantic diversity, lower concreteness, lower frequency and shorter phonological forms display stronger tendencies toward verbal expansion. These lexical properties jointly determine how firmly a noun is anchored at the nominal pole of the noun–verb continuum. Overall, the findings portray the dynamics of conversion as a product of communicative pressures, allowing the English lexicon to achieve greater expressivity with fewer but more flexible forms.