The National Highways, the majority 2 laned (one in each direction), constitute a total of about 65,000 km, out of which 5,840 km is to be converted into "Swarna Chathuspatha" or Golden Quadrilateral, a prestigious project commenced by the NDA Government led by Mr. Atal Bihari Vajpayee.(Source, The Hindu, Dt. June 7, 2008 : Mr. H. T. Muniapppa, Union Minister ofo State for Surface Transport) of which 4,885 km are median-separated express highways. In some more developed areas it may broaden to 4 lanes. Closer to big cities, highways can even be of 8 lanes. Highways in India are around 2% of the total road network in India, but carries nearly 40% of the total road traffic. The National Highways (Amendment) Bill, 1995, provides for private investment in the building and maintenance of these arteries of India.
| NH | Route inside Bihar | Complete Route | Length in State (km) | Total Length |
| 2 | Uttar Pradesh border – Mohania – Kudra – Sasaram – Dehri – Aurangabad – Madanpur – Dobhi – Barachati – Jharkhand border | Delhi – Mathura – Agra – Kanpur – Allahabad – Varanasi – Mohania – Barhi – Palsit – Baidyabati – Bara – Calcutta | Delhi (12), Haryana (74), Uttar Pradesh (752), Bihar (202), Jharkhand (190), West Bengal (235) | 1465 |
| 19 | Uttar Pradesh border – Manjhi – Chhapra – Sonpur – Hajipur – Patna | Ghazipur – Balia – Manjhi – Chhapra – Sonpur – Hajipur – Patna | Bihar (120), Uttar Pradesh (120) | 240 |
| 28 | Junction with NH 31 – Barauni – Bachwara – Tajpur – Muzaffarpur – Mehsi – Chakia – Gopalganj – Uttar Pradesh border | Junction with NH 31 – Barauni – Muzaffarpur – Pipra – Kothi – Gorakhpur – Lucknow | Bihar (259), Uttar Pradesh (311) | 570 |
| 28A | Junction with NH 28 – Pipra – Kothi – Sagauli – Raxaul – Indo-Nepal Border | Junction with NH 28 – Pipra – Kothi – Sagauli – Raxauli – Indo-Nepal border | Bihar (68) | 68 |
| 28B | Chapra – Bettiah – Lauriya – Bagaha – Chhitauni – Uttar Pradesh Border | Chapra – Bettiah – Lauriya – Bagaha – Chhitauni – Uttar Pradesh border | Bihar (121) |
| 30 | Junction with 2 – Mohania – Kochas – Dinara – Bikramganj – Arrah – Danapur – Patna – Fatuha – Bakhtiarpur | Junction with NH 2 – Mohania – Arrah – Patna – Bakhtiarpur | Bihar (230) | 230 |
| 30A | Fatuha – Chandi – Harnaut – Barh | Fatuha – Chandi – Harnaut – Barh | Bihar (65) | 65 |
| 31 | Jharkhand border – Rajauli – Nawada – Bihar Sharif – Bakhtiarpur – Barh – Mokameh – Barauni – Begusarai – Balia – Khagaria – Bihpur – Kursela – Purnia – Baisi – West Bengal – Kishanganj – West Bengal border | Junction with NH 2 – Barhi – Bakhtiarpur – Mokameh – Purnea – Dalkola – Siliguri – Sevok – Cooch Behar – North Salmara – Nalbari – Charali – Amingaon Junction with NH 37 | Bihar (393), West Bengal (366), Assam (322), Jharkhand (44) | 1125 |
| 57 | Muzaffarpur – Darbhanga – Jhanjharpur – Narahia – Narpatganj – Forbesganj – Araria – Purnia | Muzaffarpur – Darbhanga – Jhanjharpur – Narahia – Narpatganj – Forbesganj – Araria – Purnia | Bihar (310) | 310 |
| 57A | Junction with 57 – Forbesganj – Jogbani | Junction with NH 57 – Forbesganj – Jogbani | Bihar (15) | 15 |
| 77 | Hajipur – Muzaffarpur – Sitamarhi – Sonbarsa | Hajipur – Muzaffarpur – Sitamarhi – Sonbarsa | Bihar (142) | 142 |
| 80 | Mokamah – Luckeesarai – Munger – Bhagalpur – Kahalgaon – Jharkhand border | Mokamah – Luckeesarai – Munger – Bhagalpur – Kahalgaon – Rajmahal – Farrakka | Bihar (200), Jharkhand (100), West Bengal (10) | 310 |
| 81 | Kora – Katihar – Malda – West Bengal border | Kora – Katihar – Malda – West Bengal Border | Bihar (45), West Bengal (55) | 100 |
| 82 | Gaya – Hisua — Rajgir – Bar Bigha – Bihar Sharif – Mokameh | Gaya – Hisua — Rajgir – Bar Bigha- Bihar Sharif – Mokameh | Bihar (130) | 130 |
| 83 | Patna – Jehanabad – Bela – Gaya – Bodhgaya – Dobhi | Patna – Jehanabad – Bela – Gaya – Bodhgaya – Dobhi | Bihar (130) | 130 |
| 84 | Arrah – Buxar | Arrah – Buxar | Bihar (60) | 60 |
| 85 | Chhapra – Ekma – Siwan – Gopalganj | Chhapra – Ekma – Siwan – Gopalganj | Bihar (95) | 95 |
| 98 | Patna – Arwal – Daudnagar – Aurangabad – Rajhara – Amba – Jharkhand border | Patna – Arwal – Daudnagar – Aurangabad – Rajhara – Amba – Jharkhand border | Bihar (156), Jharkhand (51) | 207 |
| 101 | Chhapra – Baniapur – Mohammadpur | Chhapra – Baniapur – Mohamadpur | Bihar (60) | 60 |
| 102 | Chhapra – Rewaghat – Muzaffarpur | Chhapra – Rewaghat – Muzaffarpur | Bihar (80) | 80 |
| 103 | Hajipur – Hazrat Jandaha – Mushrigharari | Hajipur – Hazrat Jandaha – Mushrigharari | Bihar (55) | 55 |
| 104 | Chakia – Madhubani – Jaynagar – Shivhar – Sitamarhi – Sursand – Jaynagar – Narahia | Chakia – Madhubani – Jaynagar – Shivhar – Sitamarhi – Sursand – Jaynagar – Narahia | Bihar (160) | 160 |
| 105 | Darbhanga – Aunsi – Jaynagar | Darbhanga – Aunsi – Jaynagar | Bihar (66) | 66 |
| 106 | Birpur – Pipra – Madhepura – Kishanganj – Bihpur | Birpur – Pipra – Madhepura – Kishanganj – Bihpur | Bihar (130) | 130 |
| 107 | Maheshkhunt – Sonbarsa Raj – Simri-Bakhtiarpur – Bariahi – Saharsa –Madhepura – Banmankhi – Purnia | Maheshkhunt – Sonbarsa Raj – Simri Bakhtiarur – Bariahi – Saharsa – Madhepura – Banmankhi – Purnia | Bihar (145) | 145 |
| 110 | Junction with NH 98 – Arwal – Jehanabad – Bandhuganj – Kako – Ekangarsarai – Bihar Sharif – Junction with | Junction with NH 98 – Arwal – Jehanabad – Bandhuganj – Kako – Ekangarsarai – Biharsharif – Junction with NH 31 | Bihar (89) | 89 |