Led by Derek Wood, a 10th generation Louisianian who studied history at Tulane, six of us riders (from Toronto, Boston and Raleigh, N.C.) started just outside the French Quarter and rode east. We soon began to pass a piece of Katrina's legacy I hadn't seen much of yet: the "X" markers that rescue teams emblazoned on houses to indicate that they had been checked. Each quadrant of the "X," Wood explained, included the date, the team that conducted the search, whether entry was made and what, if anything, was found inside. The markers appeared randomly, sometimes two beside each other, then none for several blocks. They existed in various states; some had been left alone for the last 10 years, some peeked through a thin coat of paint, and others had been turned into art; I saw one in Bywater that had been reconstructed in metal. I asked Wood if he minded seeing them.