Why are there so many brick buildings in Portland, Maine?

On the 4th of July, 1866, a carelessly thrown cracker set fire to a boat-builder's shop on Commercial street, whence the flames were soon communicated to Brown's Sugar House; whence it swept on diagonally through the city, spreading like a fan as it went. Entire streets were swept away, includeing (sic) massive warehouses, lofty churches, splendid mansions, ancestral houses and the dwellings of the poor, in the oldest and most crowded parts of the city in one common ruin. For nearly half a day, and through the night until the small hours of the morning, the vast volumes of flame and smoke held sway, sending terror and anguish among the whole population. The fire ended near Munjoy's Hill. The morning saw fifteen hundred buildings laid in ashes; fifty-eight streets and courts reduced to a wilderness of chimneys, amid which the most familiar inhabitant lost himself; ten thousand people made homeless, and ten millions of property destroyed. Villages of tents and barracks sprang up on Munjoy, and generous contributions from abroad flowed in, providing food, shelter and clothing for the penniless.
A Gazetteer of the State of Maine
By Geo. J. Varney Published by B. B. Russell, 57 Cornhill, Boston 1886