I will begin with giving an instance from one of the state governments (that of Pennsylvania) and then proceed to the federal government.
The state of Pennsylvania, though nearly of the same extent of territory as England, was then divided into only twelve counties.

Each of those counties had elected a committee at the commencement of the dispute with the English government; and as the city of Philadelphia, which also had its committee, was the most central for intelligence, it became the center of communication to the several country committees.

When it became necessary to proceed to the formation of a government, the committee of Philadelphia proposed a conference of all the committees, to be held in that city, and which met the latter end of July, 1776.
Though these committees had been duly elected by the people, they were not elected expressly for the purpose, nor invested with the authority of forming a constitution; and as they could not, consistently with the American idea of rights, assume such a power, they could only confer upon the matter, and put it into a train of operation.

The conferees, therefore, did no more than state the case, and recommend to the several counties to elect six representatives for each county, to meet in convention at Philadelphia, with powers to form a constitution, and propose it for public consideration.
This convention, of which Benjamin Franklin was president, having met and deliberated, and agreed upon a constitution, they next ordered it to be published, not as a thing established, but for the consideration of the whole people, their approbation or rejection, and then adjourned to a stated time.

When the time of adjournment was expired, the convention re-assembled; and as the general opinion of the people in approbation of it was then known, the constitution was signed, sealed, and proclaimed on the authority of the people and the original instrument deposited as a public record.