In the eponymous valley, the city of Simi Valley is located in the southeast corner of Ventura County, California, USA, 40 miles from downtown Los Angeles, making it part of the Greater Los Angeles Area. The town sits alongside Thousand Oaks, Moorpark, and Chatsworth. Cities are expected to have a population of over 125,000. Ronald Reagan Presidential Library is located in Simi Valley WHERE the former president was buried in 2004. The total area of the City is 42,2 square miles.