From Brownstoner Brooklyn: "As in many things New York, we can thank the Dutch for the stoop, both the concept and the name, which originated from the word stoep. Flooding was no longer a major concern, but the stoop gave the architect a reason for a more elaborate entryway, and stoops were immediately and universally embraced in our row house design ever since. Most New York streets did not have service alleyways, like Philadelphia and Baltimore, so the stoop allowed a service entrance to be built underneath the main stairway, to allow servants and deliveries to enter the house and kitchen. Because people eventually want change, the Anglo-Italianate style also developed.... Based on English terrace houses, these homes did not have tall stoops at all, but instead were the first 'English basement' style houses, where one entered on the ground level with only one or two stairs up, and there was no service floor below." Full article here.