  We prove the following theorem. Suppose that $M$ is a trim DFA on the Boolean
alphabet $0,1$. The language $\L(M)$ is well-ordered by the lexicographic order
$\slex$ iff whenever the non sink states $q,q.0$ are in the same strong
component, then $q.1$ is a sink. It is easy to see that this property is
sufficient. In order to show the necessity, we analyze the behavior of a
$\slex$-descending sequence of words. This property is used to obtain a
polynomial time algorithm to determine, given a DFA $M$, whether $\L(M)$ is
well-ordered by the lexicographic order. Last, we apply an argument in
\cite{BE,BEa} to give a proof that the least nonregular ordinal is
$\omega^\omega $.
