The first addition to the town, west of Fourth Street, appeared in 1816. It was called "Lucas Addition on the Hill" and reached west to Seventh Street from St. Charles to Spruce. J. B. C. Lucas, who purchased this part of the old Commonfield, set aside the present block now occupied by the Old Courthouse as a public square. He also donated a space for a public market along what is now Twelfth Street between Olive and Chestnut.
Subdivision activity "on the Hill" increased appreciably after St. Louis became a city in 1822, when land owners such as Lucas, William C. Christy and Jeremiah Connor platted new additions. Connor acquired a long narrow strip 380 feet wide from Fourth Street to the western limit of the Commonfield at what is now Jefferson Avenue. Along its center he laid out the present Washington Avenue with 150 foot deep lots on each side, but with no provision for cross streets. Later these were cut through by condemnation. Lack of regulation led to many irregularities in street locations and block sizes in these early subdivisions creating traffic problems to be corrected by cut-offs and street widenings in later years.
However, the streets "on the Hill" were wider than those in the old town and by 1829 several had been paved and the limestone bluff had been graded to provide access to the river. About this time, the main roads from the town became better defined. These included what is now Broadway, south to Carondelet and north to the village of North St. Louis. Westwardly, Market Street, Olive Street and the road to St. Charles came into general use. Better access to the river led to the erection of the first warehouses on Front Street along what later became the levee. Main (First) Street began to assume a commercial character by 1830 when several stores supplanted the old French houses, whose owners moved out because of space limitations. They relocated in country places west of Twelfth Street. Thus began the process of decentralization in the City.
The industrial revolution, which had arrived in St. Louis with the arrival of the first steamboat in 1817, was now in full swing. Steamboats lined the levee and steam was in use to propel machinery in many mills and factories in the City, as coal supplanted wood as fuel.