Signature Rock (Site 48BH188) is a large amphitheater-like sandstone cliff located between Cowley and Byron, Wyoming, north of the Shoshone River. Names and dates incised on sandstone rock formations at Signature Rock in 1864 correspond to the individual dates of various Shoshone River crossings and layovers. For example, Benton Garinger of Ohio left his name for posterity on June 19. He may have been a member of Bridger's train, but more likely was a member of one of the trains led by either Jacobs or Allensworth. Traveling with Allensworth, Hedges stayed in camp on June 19 and 20. Stanfield laid over on June 19, and on the 20th, he "traveled a short distance today. . . . stoped [sic] the rest of the day to let the stock graze . . . near small creek." This small creek was most likely Sage Creek, approximately five miles north of the Shoshone. On June 29, T. B. McNeal of Ohio added his name to the cliff face. Although it is not clear which train he was with, it appears that he accompanied the fourth train that was about eight to ten days behind Allensworth. Three weeks after Bridger's first train, J. Housel left his name on July 8. He was probably a member of Charles Baker's train that crossed the Shoshone River on July 8. Four additional names, W. M. McCoy, D. A. Leaky, Wm. Henry, and S. Magee, were added to the cliff face on July 14, corresponding to William Haskell's train that crossed the Shoshone River on July 14.

The inscriptions also indicate the route the trail took up the valley of Sage Creek. They are very significant because they substantiate the correct route of the Bridger Trail through an area with limited historic evidence concerning the trail route. The location and authenticity of the inscriptions has been confirmed by field reconnaisance.