[1] National highway 31 transits 1,047 kilometres (651 mi) across three states of India in east - west direction.

[2] Unnao, Lalganj, Raebareli, Salon, Pratapgarh, Machhlishahr, Jaunpur, Babatpur, Varanasi, Ghazipur, Ballia, Suraimanpur Chhapra, Hajipur, Patna, Bakhtiyarpur, Barh, Mokama, Barauni, Begusarai, Khagaria, Naugachhia, Katihar, Labha.

Chandpur, Harishchandrapur, Tulsihata, Chanchal, Malatipur, Samsi, Akalpur, Kodubari Morh at Gazole.

As per Satellite imagery from Google Maps, the national Highway 31 is being made 4 lane currently between Unnao & Raebareli, between Ghazipur & Ballia, between Bakhtiyarpur & Barauni, between Katihar & Labha.

Once these bypasses are built, the Highway length will shorten to 992.25 kilometres (616.56 mi) & reducing travel time.