When the Erie Canal was opened on Oct. 26, 1825, the fact was known in New York City, 425 miles away, within 81 minutes. This was before the advent of radio or telegraph. How was it done?
Cannons were placed along the length of the canal and the Hudson River, each within earshot of the last. When the crew of each cannon heard the boom of its upstream neighbor, it fired its own gun.
As a result, New Yorkers knew within an hour and half that they had a navigable route to the Great Lakes — the fastest news dispatch, to that date, in world history.
10/07/2013 Wait, that last bit ain’t right — Claude Chappe’s semaphore telegraph covered 120 miles in 9 minutes in 1792. (Thanks, Michael and Lorcan.)