Feldgrau.net

phylo_roadking wrote:... even after December 7th 1941, the Japanese reached an agreement with the NEUTRAL - to them - USSR that US ships supplying via Vladivostock could continue! ....

Arkhangelsk was a larger port than Murmansk and better equipped for accepting and handling war supplies.
However, the White Sea froze over in mid-December and could stay closed to navigation until the end of May.

This route, joining Soviet territory to warm water across the mountains and deserts of Iran, was one of five by which 171 /2 million long tons of lend-lease supplies were carried from Western Hemisphere ports to Soviet destinations. It is difficult to visualize 171/2 million long tons in .the abstract; but 2,803 ships crossed the seas to carry them, a fleet more than nine times as numerous as that which mounted the Anglo-American invasion of North Africa in November 1942. The total tonnage figure nearly matches the 22 million long tons landed on the Continent of Europe for the American forces between January 1942 and May 1945. Russia's share of the common pool was therefore considerable, befitting her share in the common conflict

Comparative Score
In the world-wide effort to deliver war supplies to Soviet Russia, how does the record of the Persian Corridor compare with that of the other routes from the Western Hemisphere? There were five routes: the Soviet Arctic, the Black Sea, the north Russian, the Persian Gulf, and the Soviet Far East.
The least important route, tonnage wise, was that which led from American Pacific ports to Siberian ports on the Arctic Ocean. Because the Arctic ports were ice free only during the summer months, sailings were restricted to those periods. The main military significance of the route was that aviation fuel was transported over it for an air ferry route across Siberia which, because of Soviet opposition, never materialized. Total tonnage was 452,393 long tons.32
Next in tonnage accomplishment was the Black Sea route, the last to be inaugurated. It was made possible by clearing the Axis from the Mediterranean and the Black Sea ports of Odessa, Constanta, and Novorossiysk. In 1944 the Andimeshk truck assembly plant and a number of PGC portal cranes were transferred to the USSR for installation at these ports. First ships arrived in January 1945. During the five months of operation of the route 680,723 long tons were delivered.
British convoys first sailed to the north Russian port of Murmansk in August 1941. Archangel served as an alternative port. This was the shortest route from American ports to the USSR, 4,500 miles, and required twenty-one days' running time and five weeks' convoy time. Inland clearance distance by rail from the ports to the battle front and industrial centers was satisfactorily short. During the last three months of 1941 and the first four months of 1942 the rate of shipments to north Russian ports was greater than by any other route then in use from the Western Hemisphere to Soviet ports; but the increasing severity of Axis attacks upon shipping in northern waters reduced its use drastically until July 1944, by which time an improvement in its safety reopened it to year-round activity. It did not again become a main artery of Soviet supply, for by that time it had been rivaled by the Soviet Far East and Persian Gulf routes. Its total of 3,964,231 long tons was nearly equal to that of the Persian Gulf.
Longest in mileage and ship round-trip time, the Persian Gulf route was nevertheless desirable because of its relative safety, its all-year usefulness, and its accessibility to Soviet territory if other routes should be denied. The difficulties of providing and operating adequate port and inland clearance facilities were substantial handicaps in operation of the Gulf route; but so long as other routes were threatened either by military denial or, in the case of the Far Eastern route, by a sudden change in Japan's attitude toward its use, the Persian Gulf remained a necessity. In receiving 4,159,117 long tons of Soviet-aid cargo from the Western Hemisphere, the Gulf was excelled only by the Far Eastern route.
Almost half, or 47 percent, of Russian-aid supplies from the Western Hemisphere reached the Soviet Union via a sea lane which extended from American Pacific ports around to the north of Honshu to eastern Siberian ports. The total tonnage via this route came to 8,243,397 long tons; but, because of the peculiar situation by which Japan winked at the traffic to her ally's enemy, only supplies classified as nonmilitary were carried.
The significance of the Persian Gulf route is measured by its tonnage accomplishment and its fulfillment of strategic necessity. Its handicaps were less serious than those which at one time or another afflicted the other routes; its advantages more solid and continuous. Development of the Persian Gulf line of communications to the USSR was clearly basic to global planning.