Because the dollar sign appeared in ledgers before the United States was a fully formed nation, historians have had to piece together its ancestry through a series of intriguing, if sometimes flawed, hypotheses.1. The Spanish Pillars of HerculesOne of the most visually compelling theories...

Before Washington, D.C., became the permanent seat of American power, the U.S. capital was essentially a government on wheels. Between 1776 and 1800, the capital moved across nine different cities as Congress fled from British bayonets, angry mutineers, and the logistical hurdles of a...