In Colorado

Roy Peterson lived for a short time in Colorado before moving to Washington State.  The information I have is sketchy but I do have one good clue here:

In Tacoma

The 1945 Tacoma City Directory list a Roy F. Peterson with a wife named Bertha that lived at 280 Omak. He was a welder at the Todd Pacific Shipyard.

Todd Pacific was known as the Seattle-Tacoma Shipbuilding Corp. until June of 1944 when they changed their name. The Seattle-Tacoma Shipbuilding Corp. (Todd Pacific after June 1944) was a major builder of ships for the U.S. Navy. They built all kinds of ships - but mostly transports and "baby flat-tops".

Why move to Tacoma?  Grandpa was a Welder and Tacoma needed welders...

Berkeley Daily Gazette, 27 Feb 1945

I wonder if grandpa had a hand in building any of the big navy ships used in the second world war?

 Spokane Daily Chronicle, 30 April 1945

Here is an interesting/funny article from the same time period:

Toronto Daily Star, 27 June 1945

The following picture was taken in Tacoma.

In this photo is Bertha Lawson Peterson and four of her and Roy Peterson's kids: 

Velma & Don (holding hands), Charles & Olen Peterson.

Sources:

• e-Mail from Bob Schuler, Special Collections, Tacoma Public Library
• Berkeley Daily Gazette, 27 Feb 1945
• Spokane Daily Chronicle, 30 April 1945
• Toronto Daily Star, 27 June 1945