How did "$" come to represent US currency?

Christopher Beam writes an interesting piece on the origins of some world currencies.

The evolution of the US dollar’s “$” symbol is relatively complex compared to other well-known currency symbols:

We got the $ from the Spanish. In the late 18th century, merchants in the North American British colonies traded mainly with two currencies: the British pound and the Spanish dollar. When the United States adopted its own currency in 1785, it used Spanish money as its model—a deliberate “screw you” to the British.

Scholars have since theorized that the $ sign evolved out of an abbreviation for peso: The plural for pesos was “ps,” which eventually became “ps,” and then simply an “S” with a single stroke denoting the “p.”