  In any Coxeter group, the conjugates of elements in the standard minimal
generating set are called reflections and the minimal number of reflections
needed to factor a particular element is called its reflection length. In this
article we prove that the reflection length function on an affine Coxeter group
has a uniform upper bound. More precisely we prove that the reflection length
function on an affine Coxeter group that naturally acts faithfully and
cocompactly on $\R^n$ is bounded above by $2n$ and we also show that this bound
is optimal. Conjecturally, spherical and affine Coxeter groups are the only
Coxeter groups with a uniform bound on reflection length.
