After ten years of art education, McKimson went to work for Walt Disney. He stayed with Disney's studio for two years before moving to that of Hugh Harman and Rudolf Ising. In 1946, McKimson was promoted to director, a position he shared with Friz Freleng and Chuck Jones until the closing of the Warner Bros. cartoon studio in 1964. During this period, McKimson created the character Foghorn Leghorn and directed every cartoon starring the character, every Hippety Hopper/Sylvester pairing, and every Tasmanian Devil short.
Critics, perhaps unfairly, routinely dismiss McKimson's work -- that is, when the critics deem to discuss McKimson's work at all. Much of this critical neglect likely stems from two factors: McKimson's early death, and his extreme shyness. He died well before animation became a respected artform, and when he was alive, he gave few interviews. His shorts are described as having a "squarer" style than his fellow directors, Freleng and Jones. Critics describe his style as somewhat prosaic, not as innovative or impeccably crafted as the films of Jones or Freleng. In many ways, his cartoons, extremely violent and irreverent, are a continuation of the style of Bob Clampett, who had left the studio a few years before McKimson's promotion to director.
But if McKimson's cartoons did not reach the "intellectual" heights of Jones or enjoy the musical freedom of Freleng, he is seen by animation scolars as being the most artistically talented of the Termite Terrace cartoon directors. In 1942 McKimson drew a single portrait of Bugs Bunny, leaning against a tree and smiling as he was eating a carrot, that became known as the definitive portrait of the character; this picture has been imitated many times by later artists, including McKimson's peers. Even when Warner Bros. acknowledged the influence of UPA and abandoned extreme "realism" in cartoons during the early 1950s, the characters in McKimson's cartoons were the best-looking and most lifelike.
In 1953, however, the Warner Bros. cartoon studio laid off most of its staff for six months. McKimson had to rebuild his unit, which never regained the vivid animation of earlier years. Most of McKimson's "earthbound" cartoons were released from 1955 on, although he still made some good shorts -- even from the much lower budgets of the post-1964 era.
Reference: Remembering Robert McKimson