☛ The New Yorker: “March to April”, cover art by Saul Steinberg, March 26, 1966. © Condé Nast.
This illustration is not the only one Steinberg did on the theme of seasonal transition. Two years later, in 1968, he created an illustration about the transition from February to March (see previously here: “February to March” by Saul Steinberg, 1968).
The New Yorker cover featuring Steinberg illustration is reproduced in Steinberg at the New Yorker edited by Joel Smith in 2005 (p. 99; Amazon). It appears in a section titled “Cat People” where are gathered examples of Steinberg’s drawings featuring cats. The following explanation is provided:
“I am a cat,” Steinberg replied, when asked why his cats resembled his people as well as himself. In his art, the feline is no animal but humanity discreetly masked, with all the confident self-absorption of a dignified species. […] The cat implacability and focus make it an apt figure for the onward push of time, as on a cover published in the spring of 1966. February is an iceberg melting on the forgotten horizon, summer only a vague promise on the page ahead, but here and now March passes vividly into April as a cat rides a bicycle over a wandering stream. (Harry N. Abrams, 2005, p. 94)
“March to April” is also reproduced without the New Yorker cover design (illustration only) in the book Saul Steinberg edited by the Whitney Museum of American Art in 1978 (New York, with text by Harold Rosenberg, p. 132; Amazon, used copies are easily found online at very reasonable prices). I found a large format reproduction of it at Being Akin (posted online on April 1st, 2011):
Steinberg created different versions or variations of “March to April” during the years 1965-1966. One version was auctioned on Artnet where only a thumbnail image of it is available (notice the color of the clouds). This earlier version was titled “March-April V”. Along with three other versions, it is reproduced in black-and-white in the Whitney Museum of American Art catalog (New York, 1978, pp. 62-63):