Above the level of the river, Poti is extremely unhealthy, fever and ague prevailing in summer and autumn.
This railway, together with the driving roads over the Caucasus mountains via the Mamison pass (the Ossetic military road) and the Darial pass (the Georgian military road), and the route across the Black Sea to Poti or Batum are the chief means of communication between southern Russia and Transcaucasia.
The Treaty of Adrianople, by which the Danubian principalities were erected into practically independent states, the treaty rights of Russia in the navigation of the Bosporus Anapa and Poti in Asia ceded to the tsar, included also a settlement of the Greek question on the terms of the protocol of the 22nd of March.
This was notably the case with the claim of Russia to Poti and the valley of the Rion (Phasis), which was still outstanding at the time of the congress of Vienna (1814-1815) and prevented the question of a European guarantee of the integrity of Turkey from being considered.
It is in this valley that the principal towns (except Vladikavkaz at the north foot of the Caucasus) of Caucasia are situated, namely, Baku (179,133 inhabitants in 1900), Tiflis (160,645 in 1897), Kutais (32,492), and the two Black Sea ports of Batum (28,512) and Poti (7666).
A third line of great importance is the junction line between the Transcaucasian railway - which runs from Batum and Poti to Baku, via Tiflis, with a branch line to Kars - and the railway system of Russia proper.