BROWNSVILLE TEX JUL 15, transit CDS with matching PAID 10 rate handstamp on folded lettersheet to Messrs Avendaño Bros., New Orleans, La. from Matamoros, Mexico, with manuscript "via Berwick's Bay" early routing endorsement at top and greenish-blue "A. Uhde & Co., Matamoros" oval company sender’s handstamp, with Matamoros, Julio 8, 1861 docketing on inside flap; light corner wear and some toning along file fold, ex Weatherly. THE ONLY KNOWN TRANS-RIO GRANDE MAIL USE BEARING THE "VIA BERWICK'S BAY" ROUTING DIRECTIVE. Listed in both Miscellaneous-1 and Texas sections. $1,600.