I am still not convinced this was ever a Scottish tradition, but it's still a nice one.
It's not, Sherry. The real history behind the Kirkin' Service dates to the Second World War, when Rev. Peter Marshall, Pastor of the New York Ave. Presbyterian Church and an immigrant from Coatbridge, Scotland, used the service as a way to raise funds for British War relief. Dr. Marshall was a member of the Washington DC St. Andrew's Society, and the service was picked up by them -- first held at Dr. Marshall's church, it was soon being held at the National Cathederal. It is a Scottish-American church parade.

Cheers,

Todd