Adding to the difficulties of land travel the dangers of the river tide, the difficulty of securing boats, and their great cost, it is little wonder that emigrants from Virginia preferred the long but better-known land route, through Powell's Valley and Cumberland Gap to the Braddock Road and the Ohio River. At a later date, however, the difficulties of river passage were materially decreased and the Ohio became the great outward emigrant route. But for the return traffic from Kentucky to Virginia, there was no comparison between the ease of the land route and the water route. Mr. Speed affirms that the road through Cumberland Gap "was the only practicable route for all return travel."[24] Of course for a long period there were no exports from Kentucky, as hardly enough could be raised to feed the multitude of immigrants; but when at last Kentucky strode to the front with its great harvests of wheat and tobacco, the Mississippi and Ohio ports received them. The East received comparatively little benefit, in a commercial way, from Boone's Road; but in the earliest days that slight track furnished a moral support that can hardly be exaggerated. The vast population that surged westward over it was a mighty barrier which protected the rear of the colonies from the savages, until savage warfare was at an end. Though the frontiers of New York, Pennsylvania, and Virginia suffered greatly during the Revolution, it was Kentucky that was the thorn in the side of the British; Kentucky drew the fire of both British and Indians which otherwise would have desolated the rear of the eastern colonies, and necessitated a greater number of men than could possibly have been maintained there. It was not at Fort Pitt that the British were constantly striking, but at the Kentucky "stations;" it was not up the Allegheny or Monongahela that Colonel Burd pushed his keel boats, but up the Licking. This fact is splendidly urged by Col. John Floyd, in a letter to the governor of Virginia written on the sixth of October, 1781, in a plea for assistance in maintaining the Kentucky settlements: