Notes of the 250th anniversary of the United States, from a Kingston, NJ perspective.
June 23-25, 1775 – Washington travels through Kingston going north.
George Washington had just been appointed General and Commander in Chief by the Continental Congress meeting in Philadelphia. Because of distance and the desire for accuracy, reports of the British victory in the June 17 “Battle of Bunker Hill” (actually Breeds Hill) had not come south to Philadelphia.
Washington rode from Trenton to (new) Brunswick, through Kingston on the 23rd or 24th of June. During this period he stopped keeping a personal diary and had not begun with his officer’s diary, but did write the Congress from New York. That letter is dated June 24, but is said to be written on June 25.
The South Brunswick Historical Society had a discussion of this event on Youtube: HERE
The group traveling to New York via the King’s Highway included: Philip Schuyler, Abraham Markoe and an escort troop of horsemen he sponsored -the Philadelphia Light Horse, Charles Lee, Roger Sherman, and Joseph Reed.
The presenter, Ed Belding, believes that they spent the night in Kingston, but he has no written history of the actual journey.

Sources:
Washington, George. George Washington Papers, Series 3, Varick Transcripts, 1775 to 1785, Subseries 3A, Continental Congress, 1775 to 1783, Letterbook 1:- Sept. 22, 1776. – September 22, 1776, 1775. Manuscript/Mixed Material. https://www.loc.gov/item/mgw3a.001/.
https://boston1775.blogspot.com/2013/05/the-slow-spread-of-official-news-about.html