  The Bowen-York family of spinning black hole initial data depends essentially
on one, positive, free parameter. The extreme limit corresponds to making this
parameter equal to zero. This choice represents a singular limit for the
constraint equations. We prove that in this limit a new solution of the
constraint equations is obtained. These initial data have similar properties to
the extreme Kerr and Reissner-Nordstrom black hole initial data. In particular,
in this limit one of the asymptotic ends changes from asymptotically flat to
cylindrical. The existence proof is constructive, we actually show that a
sequence of Bowen-York data converges to the extreme solution.
