House prices in streetcar suburbs vary by neighborhood and city. Lots left empty in these areas during initial development, or where the initial houses have burned or been torn down, are usually too narrow for modern residential zoning regulations, meaning that it is difficult to infill housing in well-preserved streetcar suburbs. Occasionally two lots are combined into one for a wide enough lot, or many houses are torn down for a new use as needed. However, in some cases where historic zoning applies, infill housing is encouraged or required to match neighboring housing standards.