The first "Best in Show" winner at Westminster in New York City was in 1907. This first "Best in Show" winner was a smooth fox terrier that looked a little bit like today's Jack Russell.
Fox terriers won again in 1908, 1909, 1910, 1911, 1915, 1916, 1917, 1926, 1928, 1930, 1931, 1934, 1937 and 1942.
A Sealyham (another working breed ruined by the show ring) won in 1924, 1927 and 1936.
Airedales made Best in Show in 1912, 1919, 1920, 1933, and 1936.
A bull terrier went Best In Show in 1918, and a Welsh Terrier in 1944.
As you can see, almost all the early winners were terriers, and most of them were fox terriers. It was during this period that the face of the fox terrier was elongated and the chest enlarged by show ring breeders. Prior to World War II, if you were really intent on wining the top award at a dog show, you went into fox terriers. Probably no breed could have survived such intense attention without being wrecked by fad, and the fox terrier certainly did not.
From: Terrierman's Daily Dose Blog >> http://terriermandotcom.blogspot.com