According to hospital historians, “The Sisters' ministry to the sick began with an unfortunate accident in front of the St. Joseph orphanage in 1874. After caring for an injured man, other cases were soon brought to the Sisters, until demand became so great that Mother Agnes Spencer obtained permission from Bishop Mullen to build the hospital.” As the Erie region expanded, the hospital quickly outgrew its original three-story home, and by 1900 a new “Old Main” annex was established, followed by the creation of a nursing school (1901); yet another annex (E Building in 1911); a nurses home (1925) and a new diagnostic building and 65-bed maternity ward (1939). All of the new facilities were built on Saint Vincent's original Sassafras Street campus. After World War II came another round of expansion, and in the 1950s hospital leaders revealed plans to build a new, air-conditioned four-story inpatient center with diagnostic, X-ray, physiotherapy, lab and clinical facilities, and remodeling of business quarters. It 1978, a helipad was added, allowing for air transport of critically ill or injured patients to and from the hospital. In the 1980s, Saint Vincent teamed partnered with nearby Hamot Medical Center to create a jointly operated “Tri-State Regional Trauma Center” and a “Tri-State Regional Cancer Center;” those partnerships have since been dissolved. By the late 1980 and early 1990s, Saint Vincent was one of the busiest hospitals in the state, necessitating additional expansion; the Saint Vincent Outpatient Surgery Center opened, and a new multi-story South Building would house maternity, intensive-care units, engineering areas, a new entrance and lobby, cardio-technical services, and the laboratory. In 2008, Saint Vincent's Neonatal Intensive Care Unit (NICU) was renovated and opened in September of that year; the new 10,000-square foot facility featured 19 individual, private pods for families to bond with their babies. That year, 2,308 babies were delivered at SVH. In 2012, Saint Vincent's board voted to pursue a “strategic affiliation” with Highmark Inc. The following year, Highmark officially created Allegheny Health Network, and Saint Vincent joined the new network as its northwestern Pennsylvania hub. In 2017, Highmark and AHN announced $115 million in capital investments for Saint Vincent and the Erie region, including a new emergency department, new operating suites, a new Women and Infants Center, and a new Health + Wellness Pavilion.