The Collaborative International Dictionary of English v.0.48:

Driftway \Drift"way`\, n.
   1. A common way, road, or path, for driving cattle. --Cowell.
      Burrill.
      [1913 Webster]

   2. (Mining) Same as Drift, 11.
      [1913 Webster]

Bouvier's Law Dictionary, Revised 6th Ed (1856):

DRIFTWAY. A road or way over which cattle are driven. 1 Taunt. R. 279; Selw.
N. P. 1037; Wool. on Ways, 1.