The prime minister said the expressway will also boost tourism at places of historical significance.
Prime Minister Narendra Modi today laid the foundation stone for the Rs 23,000 crore Purvanchal highway, saying it will transform the places it passes through.
Hours before the inauguration of the project, Samajwadi Party chief dismissed it as a "relaunch" of a project which he had inaugurated as the previous chief minister of the state.
At his public meeting in Azamgarh, PM Modi described the occasion as the beginning of a new chapter in the development of the state, particularly its eastern part.
He showered praise on the leadership of UP Chief Minister Yogi Adityanath and said the state government was working to create an atmosphere conducive for development.
"The 340-km Purvanchal Expressway will transform the towns and cities that it passes through. It would also provide swifter connectivity between Delhi and Ghazipur. New industry and institutions can develop along the expressway," he said.
After becoming prime minister, this was PM Modi's first public appearance in Azamgarh, which has proved a challenge to the BJP. The party swept the 2014 Lok Sabha election in UP but lost the Azamgarh seat to former Samajwadi Party chief Mulayam Singh Yadav.
The prime minister said the expressway will also boost tourism at places of historical significance.
PM Modi stressed that connectivity was necessary for development and said the national highway network in UP had almost doubled in the last four years.
He reiterated his vision of "Sabka Saath, Sabka Vikas", and spoke about development initiatives such as PM Awas Yojana and PM Gram Sadak Yojana.
He said the recent increase in the minimum support price (MSP) of kharif crops will immensely benefit farmers and also mentioned the Centre's initiatives for weavers in this region.
The six-lane Purvanchal Expressway, expandable to eight lanes, will connect Lucknow with the economically less developed districts like Azamgarh, Mau, Ghazipur, Faizabad, Sultanpur, Ambedkar Nagar and Amethi.
The expressway will bring about development of UP's eastern districts by connecting them to the state capital and further to Agra and New Delhi, through the Lucknow-Agra Expressway and the Yamuna Expressway, officials said.
The expressway will begin from Chand Sarai village on Lucknow-Sultanpur road (NH 731) and end at Haidariya village in Ghazipur district, about 18 km from the UP-Bihar order.