Why didn't the Spanish and France actively colonise the western part of America?

Answer 1

Strange, but from San Antonio to San Luis Obispo to San Francisco, there are a lot of things that suggest that Spain did a fairly good job of colonizing the western U.S. and Mexico.
And from New Orleans to Nacogdoches Texas, a whole French judicial system rests on French claims to everything west of the Mississippi. However, British claims on the upper Midwest, blocked development there and west for the French in spite of Montreal and Prairie du Chien, Wisconsin .
And yes, wars in other parts of the world were a distraction, which is why we were able to buy the Louisiana Purchase.

Answer 2

The Spanish did colonise the western part of America.

Answer 3

At that time in history, both were too tied up in other things...wars,etc.
The new world had not been discovered to contain the vast exploitable resources that it contains.
It was simply that neither Spain nor France had the funds available to them to cash in on on yet to be found wealth in America.