By the 1850s, just 20 years after the careful construction of Middlesbrough, cholera was sweeping across the town and some streets were condemned as unfit for human habitation. The town could not cope with this second population explosion. The civic ideals upon which Middlesbrough was created in the 1830s were discarded in the face of extreme overcrowding.
"The town arising in this way cannot wait to consider anything else than time and space; and none of either must be wasted on what is merely sanitary or laying out a district into ideal settlements"
Consequently, housing was built on an unsuitable area called the Marshes, which extended from the river, across the railway into the outskirts of town. This is now occupied by industrial estates stretching along the railway and the A66. Most accommodation only had one toilet for the whole of the street. Frequent flooding and bad drainage led to further sanitation problems.