The San Diego and Arizona Railway (SD&A) is a historic railroad that connects San Diego, California, to El Centro, California. Constructed in the early 20th century, it was designed to facilitate trade and transportation between the coastal city and the interior regions of Southern California. The railway faced numerous challenges during its construction, including difficult terrain and financial issues. The SD&A was completed in 1919 and played a significant role in the development of the region. It provided essential freight and passenger services, contributing to the economic growth of San Diego and surrounding areas. Today, parts of the railway are still in use, while others have been repurposed for recreational trails.