Until the latter part of 1863 the Union was unable to hamper the growing cotton traffic from Texas to Mexico. According to the United States Navy Department, there were frequently several hundred ships standing off the mouth of the Rio Grande depositing goods in the Matamoros-Bagdad area and picking up Texas cotton for trans-oceanic shipment. Before the war, scarcely a half-dozen vessels visited these Mexican towns each year.[73] Because the Rio Grande was an international body of water, the Union was unable to blockade it. Foreign vessels, claiming to be trading with Mexico, could not legally be denied use of it. About the only way that this trade could be neutralized was for a Federal force to seize the Texas side of the river and to establish a patrol system to intercept all cotton haulers.[74] Most cotton for the Mexican trade was transported overland by ox wagon from agricultural regions for distances of up to five hundred miles or more. Convoys of three to fifteen ponderous wagons, well equipped with food and water, would normally take about three months to complete a round trip to the Rio Grande. Once across the river, the bales would be exchanged for blankets, shoes, powder, and chemicals used in the manufacturing and servicing of weapons of war.[75] A small portion of Texas cotton was carried to the outside world by blockade runners. When the Union tightened its blockade against the southeastern part of the Confederacy, a number of runners shifted their bases of operation to the less closely patrolled coast of Texas. By 1863 Tampico, Vera Cruz, and Belize (British Honduras) had become rendezvous areas for cotton runners and cotton purchasers.[76] To gain maximum benefit from cargo space available in ships that were to run the blockade, screw-jacks were used to compress the bales of cotton into holds. It soon became a source of pride among stevedores to force the greatest number of bales into a given ship. In fact one unfortunate vessel was sunk when “over-ambitious bale handlers compressed the cargo through the bottom of the ship.”[77] Weapons and ammunition continued to be critically short in Texas. General Magruder, in 1863, estimated that 40,000 arms were needed to defend the Department of the Trans-Mississippi West.[78] With only a trickle of guns coming from outside sources, the state continued to urge local craftsmen to produce them. A cartridge factory was set up in the old land office building in Austin. Also in the capital city were a cap factory and a state foundry. Another cap factory, that used home-made machinery, was in Gillespie County. A limited number of firearms were fabricated in Rusk (Whitescarver and Campbell Co.) and near Tyler (Short, Biscoe and Co.) Elsewhere, tiny weapons shops were busy in Dallas County, and in the towns of Columbia, Lancaster, and Marshall.[79]