In 1844, the first magnetic telegraph line was being constructed between Washington and Baltimore by its inventor, Samuel F. B. Morse. The line followed the railroad tracks from Washington, through Bladensburg, and on to Baltimore. Congress had appropriated $30,000 in 1843 for the experimental telegraph line, and construction on it commenced in the spring of the following year.
One of the first tests of the unfinished line occurred just north of Bladensburg near Riversdale, the estate of Charles B. Calvert.
Text in lower-left box: National Intelligencer, Washington, Wednesday, April 10, 1844. The Magnetic Telegraph. Considerable progress has been made in the construction of the Magnetic Telegraph, the invention of Professor S. F. B. Morse, upon which a test experiment is being made under the authority of an act of Congress. The line of conductors is constructed as far on from Washington to a point on the line of the rairoad opposite to the residence of C. B. Calvert, Esq., (six miles,) and the work is making progress at the rate of about a mile a day. A trial of it was made yesterday, as the cars passed Mr. Calvert's by communicating the fact of their passage to the point at which the line begin in Washington, and an answer, acknowledging the receipt of the intelligence, was received back in two or three seconds.
Text with lower middle picture: Riversdale, the estate of Charles B. Calvert.
Text with upper right photo: Samuel F. B. Morse. Courtesy of the Library of Congress, Prints and Photographs Division.
Text with lower right photo: Morse's 1837 telegraph instrument. Courtesy of the Library of Congress, Prints and Photographs Division.