We know the US has sent lots of supplies to the Soviets during WW2 (including tanks, planes, trucks, etc.), but how did they do it? Did they transport them from Alaska to Siberia across the strait? Did they transport them through the Levant/Turkey or India->Iran to the Caucasus? Was it from India to Iran and then over the Caspian Sea or perhaps through what is today's Turkmenistan?
While the Arctic Convoy route is probably the most famous one (US <-> GB/Iceland <-> Murmask/Archangelsk) it only accounted for about 4M tons of supplies (23-ish % of the total). This was the fastest route to Russia but also the most risky since it ran perilously close to Nazi occupied Norway. Throughout the war allied escorts fought a running battle against german Aircraft, submarines and a few surface vessels. Despite this, some 93 % of the supplies sent via the arctic route reached their destination.
The second option was the Persian corridor which ran (originally) from the US to persian gulf ports and from there via railway or truck to the Soviet union. From 1943 an onwards (after the battle for the med) much of the supplies were redirected through the med instead. This route accounted for a further 27 % of the total supplies.
By far the biggest but most often forgotten route, it ran from the US west coast ports to Vladivostock, exclusively on russian ships since Japan and the USSR observed a strict non-aggression pact. From Vladivostock the goods went on the trans siberian railroad west. This route accounted for around 50 % of the total supplies delivered to the USSR during the war.
In addition to this, there was also the Alaska-Siberia Air Route (ALSIB) which was used to transport combat aircraft and air cargo to the USSR. In terms of tonnage it was relatively minor but some 8000 aircraft were delivered by this route.