Impact of the Accessibility Generated by the Mexicali–San Felipe Highway on Reduction in Marginalization Levels in the Urban Periphery and Sub-Urban Areas

The objective of this research is to determine whether levels of road accessibility in urban, peri-urban, and sub-urban localities within the municipalities of Mexicali and San Felipe, in Baja California, Mexico, can be associated with processes of territorial expansion, population growth, and changes in urban marginalization levels. This is assessed through a methodology that combines ex-ante and ex-post analysis, the use of the Urban Marginalization Index (UMI) at the AGEB scale, and a hierarchical accessibility classification (Levels A, B, and C), thereby contributing a replicable tool for analyzing socio-spatial impacts derived from road infrastructure. To this end, modernization, maintenance, and reconstruction works, as well as the construction of an interchange carried out between 2006 and 2017 along Federal Highway No. 5—specifically the Mexicali–San Felipe section—were examined in relation to the accessibility they provide to ten nearby localities. UMI values were estimated for 134 AGEB using data from 2000, 2010, and 2020, which enabled the assessment of changes in quality of life before, during, and after the execution of these works. The results show significant population growth in six localities, accompanied by territorial expansion processes. Localities with direct connection to the study corridor tended to exhibit middle to low marginalization levels, while those with indirect accessibility or direct access through another federal highway section tended toward middle to high levels, with some shifting to middle to low. It is concluded that road accessibility constitutes a relevant factor in the progressive improvement in socioeconomic conditions and quality of life in urban, peri-urban, and sub-urban areas.