Final answer:
Settlers in the Western territories succeeded due to the Homestead Act, the Transcontinental Railroad, and the presence of forts built by the U.S. government.
Step-by-step explanation:
Settlers in the Western territories succeeded due to various factors. The passage of the Homestead Act and the completion of the Transcontinental Railroad in the 19th century significantly facilitated westward migration. The Homestead Act offered free land to households willing to move west, while the Transcontinental Railroad improved transportation and trade opportunities. Additionally, the U.S. government played an active role in building forts throughout the West to aid settlers during their migration and limit conflicts with Native American tribes. The forts also served as trading posts and provided vital support for westward expansion.