It has become a summer tourist spot, all thanks to the rising popularity of Manali, and excellent roads maintained by Border Road Organization. Almost every visitor to Manali yearns to visit Rohtang Pass as one can feel and touch snow even in the peak of summer on this pass.
The pass is open from May to November, has a nasty reputation for being very dangerous because of unpredictable snowstorms and high winds. It is suggested by some linguists that the name rohtang is a Persian word meaning pile of dead bodies. This pass was ancient trade route and accidents must have been very common. The local name for this pass is a generic name of pass as there are many other passes in Lahoul and Spitti which have specific names (Kunzom La, Bara Lachala, etc.). This is suggestive of the fact that this must have been the oldest and most frequented pass in the region. The pass provides a natural cultural divide between middle Himalayas and its primarily Hindu culture, with the dry desert uplands north of the Pir Panjal (first range of the greater Himalayas; and its mainly Buddhist and Tibetan-influenced culture.
On the southern face of this pass there is a spot called Bias Kund which is the origin of river Beas.
The road through the Kullu Valley, past Manali and over the Rohtang Pass to Keylong, and Lahul and on to Ladakh, has become very busy during the summer months as an alternate a military route following Kargil Conflict and, because of the troubles in Kashmir . Traffic jams (as pictured) are common occurrences caused by the inability of military vehicles, trucks, and goods carriers to navigate the tight roads and rough terrain, compounded by, snow/ice at certain points and the large number of tourists vehicles.
There are some nice books written in Hindi and English about this pass. Rohtang ke us paar (written in Hindi), and Trekking Beyond the Habitable World (written in English) are two good sources of information on the Rohtang Pass.