1928 Mexico Newer & B/B Covers

5931- 1915, INTERESTING POSTAGE DUE COVER, .10¢ PAID WITH #348

5939- 1917, RAIL ROAD CANCELS TO SAN FRANCISCO, CA

5932- 1915, – TO CERRALVO, N.L.,POSTAGE DUE, REVOLUTIONARY OVERPRINT ON 1¢ & 4¢

5929- 1913, CANANEA, SONORA, LONE POSTAGE DUE ON COVER – GREAT COVER TO NOGALES,

5930- 1918, CANANEA, SONORA TO NOGALES, WITH BACK STAMP, 5¢ POSTAGE DUE USED AS POSTAGE. NO BACK FLAP