The telegraph network in the US was built (late 19th century) with relay stations a few hundred miles apart. The relay was an actual electromagnetic relay in t

The telegraph network in the US was built (late 19th century) with relay stations a few hundred miles apart. The relay was an actual electromagnetic relay in the telegraph office that would automatically re-send the incoming signal over the next leg of the network. Along the segments of a few hundred miles, stations along the wire were all hooked up in a sort of party-line arrangement. Presumably, the electromagnetic relays would add some some little delay on key-down and maybe on key-up, perhaps making real high-speed sending and receiving difficult. When Morse retired, around the 50th anniversary of the telegraph (1894?), somehow the US telegraph network was briefly wired together so that he could send a farewell message to all the telegraph operators across the country listening simultaneously. How that was done, IDK.