Many of the people had left home with only enough money for bus fare, the Nigerian Tribune reported.
One woman said she sold a gold earring to survive.
The highway between the Nigerian capital of Abuja and Lokoja in adjacent Kogi State to the south has been flooded by rising rivers since Friday. On Sunday, a line of vehicles that had been headed north on the highway before being swamped by the water stretched nine miles.
A pregnant woman said she had been told when she left her home in coastal Delta State that the Niger River had flooded, but she thought it was a lie until she got to Lokoja.
Travelers weren't the only ones affected. People who had taken refuge at a Red Cross camp at a primary school said they had not had adequate food since arriving on Friday.
Officials closed the Lokoja highway as flood waters continued to rise. Four alternate routes have been designated for travelers.
The flooding in Kogi State was "a national disaster," said Mike Onolemen, the federal minister of works.
At least 10,000 people have been driven from their homes by flooding caused by swollen rivers.
Six states covering virtually the entire Atlantic coast of Nigeria from Lagos to Calabar have been severely affected by flooding.