What is the cause of the second continental Congress meeting in Philadelphia in May 1775?

Answer 1

All the hotels in New York were booked through Labor Day.

Answer 2

The Second Continental Congress convenes at Philadelphia. The British now control Boston and the Massachusetts militia are laying siege to the town. The Congress has no choice but to assume the role of a revolutionary government, though it has no resources. John Adams nominates George Washington for general and commander-in-chief of the Continental Army and the Second Continental Congress unanimously agrees. Washington—one of the most experienced American officers after his service in the French and Indian War—accepts on the condition that he receive no salary. From Shmoop

Answer 3

http://www.u-s-history.com/pages/h656.html