Final answer:
New York City was the main city of the Gilded Age due to its strategic location, transportation infrastructure, growing population, and political corruption.
Step-by-step explanation:
New York City was the main city of the Gilded Age due to several factors. Firstly, its location and large harbor made it an important hub for trade and commerce, attracting businesses and industries. Secondly, the city's transportation infrastructure, including its access to the Hudson River and the Erie Canal, allowed for the efficient movement of goods and resources.
Additionally, New York City's growing population and increasing wealth during this time period made it a center of social and cultural life.
The city also experienced significant political corruption, exemplified by the political machine of Tammany Hall, which contributed to its notoriety during the Gilded Age.