Name of the family that owned Lassie for the show's first three seasons:

Miller
For the show's first three years, Lassie lived on the Miller farm near a town named Calverton. In 1957, when the child who played Jeff Miller (Tommy Retig) getting too big, the Millers gave Lassie to a recently-adopted orphan named Timmy Martin (played by Jon Provost).
Source: Total Television, McNeil, 1/1/1900

 
   
  Number of different dogs which played Lassie in the TV series:

6
While Lassie was always referred to as a female on the show, all of the dogs who played Lassie were male.
Source: Atlanta Journal Constitution, 9/10/2004

 
   
  Year Eric Knight writes "Lassie Come Home," for The Saturday Evening Post:

1938
On December 17, 1938, a story about a collie named Lassie was published in The Saturday Evening Post.
Source: Minneapolis Star Tribune, 10/28/2006

 
   
  Number of years the Lassie show ran on network television:

17
The Lassie show ran from 1954 to September 1971 on CBS, and then three more years in syndication.
Source: Total Television, McNeil, 1/1/1900