The edges of planar thin‐film strips of tin are shown to limit the supercurrent carrying capacity of the films in some cases. This edge effect is demonstrated by means of a special structure which provides two current flow‐paths through the same film. The film strip edges are included in only one of these two paths. Detailed results are given for a 4400‐Å film of tin in which dc critical currents near the Silsbee limit are observed when the edges are excluded. Including the edges reduces the critical current for this film by more than 30%. It is suggested that an evaporation process can probably be developed which leads to films which will not exhibit this edge effect. The special structure would provide a useful tool for this process development, and it can also be adapted to serve as an improved gate for thin‐film cryotrons.