These two pictures were obtained from quite different sources, but they must have been taken by the same photographer only a few minutes apart.  Can you tell which picture was taken first?  We see horse-drawn floats in the 1890 Mardi Gras parade of Rex, passing the Canal Street store of Marx Bros. Furnishers & Hatters, as mule-drawn streetcars sit on the neutral ground.  The next business to our left, at 101 Canal Street, is marked “C. A. Tyler's Son”.  The letterboard of car number 19, on the left, is signed for the Magazine Street line.  Its monitor roof is more modern than the roofs of the other streetcars in the picture, as expected for a date in the late 1880s or the early 1890s.  An ornamented octagonal building, presumably a starter's house, is seen between two of the streetcars.  One of the streetcars has a roof-mounted “Audubon Park” sign (a destination, not a route name, as New Orleans routes were usually named for the principal streets they traversed).  Two men (or boys) have climbed the pole in the left foreground for a good view of the parade.  Note the many umbrella-shaded watchers in the crowd, especially on the second-floor balconies.  The shadows tell us that it isn't raining, but the sun is hot in New Orleans, even in Februuary! — Wittemann/Albertype (upper), collection of Tim Russell (lower)

The Krewe of Rex for many years issued a drawing of their planned parade.  The picture below is taken from their 1890 artwork, and depicts the first two floats in the parade of February 18, 1890, with the theme “Rulers of Ancient Times”: “No. 1 Title Car”, and “No. 2 His Majesty Rex-Urukh of Chaldea”.  The drawings clearly match the floats in the two photos above, thus dating the photos and revealing which was taken first. — Daily Picayune, February 18, 1890, from LSU Libraries Special Collections, courtesy of Tim Russell.  My thanks to Tim for identifying this parade.