Except in the north and south ends of the island, the avenues would begin with First Avenue on the east side and run through Twelfth Avenue in the west. In addition, where the island was wider, there would be four additional lettered avenues running from Avenue A eastward to Avenue D. Some of the avenues, such as Twelfth Avenue, ran through land that did not as yet exist, but the state legislation which created the Commission also authorized the city to extend its boundaries into the Hudson and East Rivers, so the land required for these new streets would eventually be created. Broadway, an existing road, was not included in the 1811 plan, and was added to the grid later.