Why was Yokohama opened as a foreign trade port instead of Kanagawa?

Although the Harris Treaty of 1858 designated Kanagawa as a port for foreign trade and residence, the Japanese government ultimately opened the port at Yokohama instead for strategic and security reasons.12

Kanagawa was a significant post station located directly on the Tōkaidō, which was Japan’s primary east-west highway at the time. The government feared that allowing foreigners to reside and trade in such a busy, well-traveled location would lead to social friction and make it difficult to keep Japanese citizens and foreign residents separated.12

In contrast, Yokohama was a small, isolated fishing village situated away from the main highway, making it much easier to police and control. Additionally, Yokohama possessed a deepwater harbor that was considered superior to the one at Kanagawa, making it a more practical choice for a burgeoning international trade hub.12