Earlier versions of the chocolate éclair, known as “pain à la duchesse” or “petite duchesse," date as far back as the early 19th century, but the pastry was first commonly described as a chocolate éclair in the 1850s. Food history references, including the estimable Larousse Gastronomique, describe éclairs but are imprecise regarding their origin.
The éclair is probably a product of food evolution. Antonin Careme (1784-1833), a famous pastry chef for French royalty, is said to have created something akin to an éclair and, in particular, the first chocolate éclair. In French, éclair translates as "flash of lightning," conceivably inspired by the light, gleaming coating of fondant icing that tops the eclair. In the English language, the earliest reference to the éclair appeared in an 1861 article in Vanity Fair magazine.
The first appearance of the éclair in an American cookbook was in 1884. In American cuisine, the éclair, or something quite like it, became known as a "Long John," an elongated doughnut filled with custard, cream or jelly and covered in chocolate frosting. The precise culinary techniques may have evolved differently from the chocolate éclairs associated with Careme, but the Long John is similar in appearance and, to some degree, in taste to the éclair.