Final answer:
Farmers, cattlemen, and miners all contributed to the development of the western territories during the post-Reconstruction Era.
Step-by-step explanation:
During the post-Reconstruction Era, the United States began to develop its western territories. All of the following groups of Americans contributed to this development except:
a. farmers
b. cattlemen
c. miners
d. shipbuilders
Based on the provided information, the correct answer would be d. shipbuilders. While farmers, cattlemen, and miners all played a significant role in the development of the western territories, shipbuilders were not directly involved in this process. Shipbuilding was more prominent in the eastern coastal states where large rivers and the development of steamboats facilitated transportation. The western expansion was primarily driven by agriculture, mining, and cattle ranching activities.