The district where the Ganga river enters the state of Uttar Pradesh :

A river's course is traced by its point of origin and the sequence of states or districts it flows through; the district through which a river first crosses into a new state, immediately adjoining the previous state's border, is that river's entry district into the new state.

The Ganga's source stream, the Bhagirathi, begins at Gaumukh in Uttarakhand; it takes the name Ganga only after joining the Alaknanda at Devprayag, and the river then flows past Rishikesh and Haridwar, the last major town before the Uttar Pradesh border. Immediately downstream of Haridwar, the river crosses into Uttar Pradesh through Bijnor district, home to the Bijnor barrage on the Ganga, making Bijnor the district of entry.

This is corroborated by the river's onward path in the state: government river-front programmes along the Ganga in Uttar Pradesh, such as the Namami Gange padayatra, are routed starting from Bijnor and ending at Ballia, precisely because Bijnor marks the river's entry into the state and Ballia marks its exit into Bihar.

• Meerut lies in the interior Ganga-Yamuna doab of western Uttar Pradesh, away from the Uttarakhand border, so it is not where the river first crosses into the state.

• Bulandshahr does adjoin the Ganga further along its course through western Uttar Pradesh, but only downstream of the district where the river actually enters the state.

• Mathura sits on the bank of the Yamuna, not the Ganga, so it plays no part in the Ganga's entry into Uttar Pradesh.