Telegraphs commercialize in the mid-1800s. Chicago and New York exchanges can share market news instantaneously. The electromagnetic telegraph debuts in 1835, and in 1844 Congress funds a 40-mile line from Baltimore to Washington, D.C. Ten years later, 23,000 miles of wire crisscross the country. Now exchange traders can share market information with unprecedented speed. By 1866, the first trans-Atlantic cable shortens communication time with foreign markets from three days to three hours.