Final answer:
The period after the Mexican-American War was considered a golden age due to the expansion of the United States' territory, the California Gold Rush, and the establishment of Manifest Destiny.
Step-by-step explanation:
The period after the Mexican-American War is considered a golden age because it marked a significant expansion of the United States' territory, which led to economic growth and increased opportunities. The Treaty of Guadalupe Hidalgo, signed in 1848, resulted in the U.S. gaining large portions of land from Mexico, including California and New Mexico. This acquisition of new territory allowed for the development of industries, such as mining and agriculture, and fueled westward expansion.
One of the key factors contributing to the golden age was the California Gold Rush. After the war, gold was discovered in California, attracting thousands of people from around the world. The influx of people and wealth led to the rapid development of cities, infrastructure, and industries, stimulating economic growth and creating new opportunities for many individuals.
Additionally, the expansion of U.S. territory established a foundation for future economic and political dominance. The acquisition of land allowed the United States to secure valuable resources, establish trade routes, and assert its influence in the Western Hemisphere. This period also marked the beginning of the concept of Manifest Destiny, the belief that the United States was destined to expand its territory and spread its ideals across the continent.