I supposed then that others must have thought of this before me. However as Google did not turn up any evidence of others making this observation, I hereby share it.
A conspectus of the crucial roles of Massachusetts and Pennsylvania in the American Revolution follows:
Revolutionary Massachusetts (source: Wikipedia)
Massachusetts was a center of the movement for independence from Great Britain, earning it the nickname, the "Cradle of Liberty". Colonists here had long had uneasy relations with the British monarchy, including open rebellion under the Dominion of New England in the 1680s. The Boston Tea Party is an example of the protest spirit in the early 1770s, while the Boston Massacre escalated the conflict. Anti-British activity by men like Sam Adams and John Hancock, followed by reprisals by the British government, were a primary reason for the unity of the Thirteen Colonies and the outbreak of the American Revolution. The Battles of Lexington and Concord initiated the American Revolutionary War and were fought in the Massachusetts towns of Concord and Lexington. Future President George Washington took over what would become the Continental Army after the battle.
His first victory was the Siege of Boston in the winter of 1775–6, after which the British were forced to evacuate the city. The event is still celebrated in Suffolk County as Evacuation Day. In 1777, George Washington and Henry Knox founded the Arsenal at Springfield, which catalyzed many innovations in Massachusetts' Connecticut River Valley.
Boston was the center of revolutionary activity in the decade before 1775, with Massachusetts natives Samuel Adams, John Adams, and John Hancock as leaders who would become important in the revolution. Boston had been under military occupation since 1768. When customs officials were attacked by mobs, two regiments of British regulars arrived. They had been housed in the city with increasing public outrage.
In Boston on March 5, 1770, what began as a rock-throwing incident against a few British soldiers ended in the shooting of five men by British soldiers in what became known as the Boston Massacre. The incident caused further anger against British authority in the commonwealth over taxes and the presence of the British soldiers.
Boston Tea Party
One of the many taxes protested by the colonists was a tax on tea, imposed when Parliament passed the Townshend Acts, and retained when most of the provisions of those acts were repealed. With the passage of the Tea Act in 1773, tea sold by the British East India Company would become less expensive than smuggled tea, and there would be reduced profit making opportunities for Massachusetts merchants engaged in the tea trade. This led to protests against the delivery of the company's tea to Boston. On December 16, 1773, when a tea ship of the East India Company was planning to land taxed tea in Boston, a group of local men known as the Sons of Liberty sneaked onto the boat the night before it was to be unloaded and dumped all the tea into the harbor, an act known as the Boston Tea Party.
The fighting brought to a head the political opposition to the crown that had been brewing throughout the colonies, and on July 4, 1776, the United States Declaration of Independence was adopted in Philadelphia. It was signed first by Massachusetts resident John Hancock, president of the Continental Congress. Soon afterward the Declaration of Independence was read to the people of Boston from the balcony of the State House.
Revolutionary Pennsylvania (source1, source2)
First and Second Continental Congresses
The economic importance and central location of Philadelphia, Pennsylvania in the Thirteen Colonies made it a natural center for America's revolutionaries. When the Founding Fathers of the United States convened the First Continental Congress in Philadelphia in 1774, 12 colonies sent representatives.
The Second Continental Congress, which also met in Philadelphia (in May, 1775), drew up and signed the Declaration of Independence in Philadelphia but when that city was captured by the British, the Continental Congress escaped westward, meeting at the Lancaster courthouse on Saturday, September 27, 1777, and then to York. There they drew up the Articles of Confederation that formed 13 independent colonies into a new nation.
The Constitutional Convention took place from May 14 to September 17, 1787, in Philadelphia, Pennsylvania, to address problems in governing the United States of America, which had been operating under the Articles of Confederation following independence from Great Britain. Although the Convention was intended to revise the Articles of Confederation, the intention from the outset of many of its proponents, chief among them James Madison and Alexander Hamilton, was to create a new government rather than fix the existing one. The delegates elected George Washington to preside over the convention. The result of the Convention was the United States Constitution, placing the Convention among the most significant events in the history of the United States.
Pennsylvania became the second state to ratify the U.S. Constitution on December 12, 1787, five days after Delaware became the first.
Temporary US Capital (source)
Philadelphia served as the temporary capital of the United States, 1790–1800, while the Federal City was under construction in the District of Columbia.