In the 1840s, the electrical telegraph superseded optical telegraph systems (except in France), becoming the standard way to send urgent messages. By the latter half of the century, most developed nations had created commercial telegraph networks with local telegraph offices in most cities and towns, allowing the public to send messages called telegrams addressed to any person in the country, for a fee. Beginning in 1854, submarine telegraph cables allowed for the first rapid communication between continents. Electrical telegraph networks permitted people and commerce to transmit messages across both continents and oceans almost instantly, with widespread social and economic impacts. In the early 20th century the telegraph was slowly replaced by teletype networks.