The Kanvar yatra or Kavad Yatra is annual pilgrimage of devotees of Shiva, known as Kānvarias, to Hindu pilgrimage places of Haridwar, Gaumukh and Gangotri in Uttarakhand and Sultanganj in Bihar to fetch holy waters of Ganges River, Ganga Jal, which is later offered at their local Shiva temples. Ganga Jal taken from Sultanganj is poured on Baba Baidyanath at Devghar by Kanwariyas. The Yatra takes place during the sacred month of Shravan (Saawan) (July -August), according to the Hindu calendar. The Kanwar Yatra is performed by Shiva Devotees called Kanwariyas from Sultanganj to Devghar round the year. Earlier this yatra was performed in the month of Bhado, from 1960 the mela started from the month of Shavan and exted up to Dashara. Now round the year Kanwariyas take Ganga Jal from Sultangaj and travel a distance of 100 km bare footed and reach Devghar in Jharkhand. During the Basant Panchmi, Maha Shivratri and other important Hindu occasions, the number of Kanwariyas increase many fold. During a calendar year approx. 2 Crores Kanwariyas perform this holy journey.

The Yatra used to be a small affair undertaken by a few saints and older devotees until the 1990s, when it started gaining popularity. Today, hundreds of thousands of devotees from surrounding states of Delhi, Uttar Pradesh, Haryana, Rajasthan, Punjab, Bihar and some from Jharkhand, Chhattisgarh and Madhya Pradesh reach these places to participate in Kanwar Mela. In 2003, 75.5 million pilgrims reached Haridwar, with traffic growing each year. Heavy security measures are undertaken by the government and the traffic on Delhi-Haridwar national highway (National Highway 58) is diverted for the period.

Source :- Wikipedia