Modern Boston today has a population of approximately 500,000 and sprawls around the tiny peninsula upon which it was founded in 1630. Its English Puritan founders were attracted to the land because it was originally surrounded on nearly all sides by water, making it easy to defend. A deepwater harbor at its front door and a river at its back also made the town a natural choice for the Colonial capital, since 17th-century transportation and communication were largely dependent on boats. For its first 150 years, Boston was the leading Colonial port in North America, its wharves crowded with sailing vessels bound to and from every continent on the globe. Although other neighbors along the Eastern Seaboard outgrew Boston by the end of the 18th century, the city continued to amass great wealth with maritime trade throughout the 1800s, and some of the world's finest shipbuilders continued to ply their craft in Boston until well after World War II. Now that the city's economy has shifted from manufacturing to high-tech, high finance, and higher education, the revitalized piers bustle with private yachts and harbor cruise boats, while seaport warehouses find new life as apartments and offices.