I think OP was referring to how Mr. Rogers introduced the show to a Canadian viewership, not him starting the show there
It later became Mister Rogers' Neighborhood [sic], which is what we know and remember him for today.
Some of the puppets he used were first introduced in Children's Corner in the 1950s, but the first show to carry his name, in any form, and starring him, was Misterogers in Canada.