Does anyone remember this buddy movie from the 1970s?

It's about two brothers, kids, really, travelling across The States in search of their father and a special place called 'the blue' which the older brother believes they will find. After many days or perhaps weeks of searching they eventually find 'the blue'; a shimmering glade of young trees, their leaves just on the turn, almost luminescent in colour against the sun. Here the brothers run and play and revel in the long journeys end. It may have been made for TV and, equally, I may have dreamt the whole thing or just remember it wrong. I'd love to know if anyone else has seen it and knows anything more about it.