I'm having a hard time finding any place that produces a ray longer than about 900 miles. I found a spot in NW South Dakota whose shortest rays are nearly 300 miles.
The longest single ray I've found is 1089 miles around El Paso, headed northwest. There ain't much out there as long as you dodge Flagstaff and southwestern Utah.
Somehow I was able to place a pin in Quebec, which resulted in a ray of 2058 miles to the USA northwest
Try a little NE of Seattle.
Anywhere that far north seems to be skewed by lack of data from Canada. For example, I clicked NE of Seattle (on Bothell specifically) and got a 1200 mi ray that passes right through Winnipeg (pop. 700,000).