Way of the Lawless by Max Brand

It was, indeed, a grave moment, yet the chances were large that even if he met someone on the road he would not be recognized, for it had been many days since the death of Andrew Lanning was announced through the countryside. He gritted his teeth when he thought that this single burst of childish carelessness might have imperiled all that he and Jud and Pop had worked for so long and so earnestly -- the time when he could take the bay mare and start the ride across the mountains to the comparative safety on the other side.

That time, he made up his mind, would be the next evening. He was well; Sally was thoroughly mastered; and, with a horse beneath him which, he felt, could give even the gray stallion of Hal Dozier hard work, and therefore show her heels to any other animal on the mountain desert, he looked forward to the crossing of the mountains as an accomplished fact. Always supposing that he could pass Twin Falls and the fringe of towns in the hills, without being recognized and the alarm sent out.