Storms tend to reach the Merrimack Valley after dark, and by two in the morning the Basiliere Bridge is empty except for the plows. Mulligan's Snow Removal Services keeps those hours — plowing driveways and lots, shoveling walks and front steps, laying salt and sand where the wind has scoured the pavement bare and slick. Haverhill's streets climb away from the river fast enough that a single storm can be rain at the water and heavy snow six blocks up the hill. The work is finished properly when nobody has to think about it at all: a car backs out at six, takes the corner, and reaches the highway without ever learning what the night looked like.