Stable geometric dimension of vector bundles over even-dimensional real projective spaces Martin Bendersky, Donald M. Davis, and Mark Mahowald mbenders@shiva.hunter.cuny.edu dmd1@lehigh.edu mark@math.northwestern.edu Abstract In 1981, Davis, Gitler, and Mahowald determined the geometric dimension of stable vector bundles of order 2^e over RP^{2n} if e > 74 and n is sufficiently large. In this paper, we use the Bendersky-Davis computation of v1-periodic homotopy groups of SO(m) to determine this geometric dimension for all values of e (still provided that n is sufficiently large). The same formula that worked for e>74 works for e>5, but for e \le 5 the geometric dimension is often different due to anomalies in the v1-periodic homotopy groups of SO(m) when m<11.