The army that Washington inherited in early July 1775 consisted of units from half a dozen New England provinces, each differing in size and composition. To be a true unified command, the Continental Army required units with consistent tables of organization and equipment.
"These are Matters of some Importance, but I am embarrassed with a Difficulty of a superiour kind. The Estimate made in Congress, supposed all the Regiments to be formed upon one Establishment, but they are different in different Provinces; & even vary in the same Province, in some Particulars. In Massachusetts, some Regiments have Ten Companies, others Eleven; The Establishment of the former is 590 Men Officers included, of the latter 649. The Establishment of Rhode Island, & New Hampshire is 590 to a Regiment, Officers included. Connecticut has 1000 Men to a Regiment. Should the Massachusetts Regiments be completed; with the new Levies from Rhode Island & Connecticut and the Riffle Men, the Number will exceed 22,000. If they should not be completed, as each Regiment is fully officer’d, there will be a heavy Expence to the Publick."
George Washington to John Hancock, 4-5 August 1775founders.archives.gov
https://history.army.mil/Publications/Publications-Catalog/The-Canadian-Campaign/