Hi,
I think it should be Walmer Bridge which is South West of Preston
BUT I notice that on the 1871 census they have daughter Mary born Preston when it appears she was registered in the sub district of Holcombe

see
www.lancashirebmd.org.uk.
There is no apparent birth for a Mary Ellen Clarke in the Preston area in the time frame, but it didn`t become a fineable offence to not register a birth until 1876.
I am becoming increasingly fond of the Mary Ellen Clarke aged 19 born America and living in Holcombe on the 1861 census with her widowed mother and siblings. On the 1851 she is listed as Ellen born Bury, but her sister Hannah was born America! Do you have Mary Ellens address from her marriage certificate?
Your Mary Ellen will not appear on the 1841 census as it was taken before she was born.
Regards.
Mo