North of Causeway Street filling begins.

The Boston & Lowell Railroad fills an area north of Causeway Street around today’s O’Neill Federal Building in just five months.  The fill is obtained by entirely cutting down Pemberton Hill, prompting some wags to claim, incorrectly, that North Station is built on Beacon Hill.  In the 1840s the railroad filled additional flats to the northwest in the vicinity of today’s Nashua Street.