"Renaissance II" project followed in 1977, focused on cultural and neighborhood development. The industrial base continued to expand through the 1970s, but beginning in the early 1980s both the area's steel and electronics industries imploded during national industrial restructuring. There were massive layoffs from mill and plant closures. In the later 20th century, the area shifted its economic base to education, tourism, and services, largely based on healthcare/medicine, finance, and high technology such as robotics. Although Pittsburgh successfully shifted its economy and remained viable, the city's population has never rebounded to its industrial-era highs. While 680,000 people lived in the city proper in 1950, a combination of suburbanization and economic turbulence resulted in a decrease in city population, even as the metropolitan area population increased again. During the late 2000s recession, Pittsburgh was economically strong, adding jobs when most cities were losing them. It was one of the few cities in the United States to see housing property values rise. Between 2006 and 2011, the Pittsburgh metropolitan statistical area (MSA) experienced over 10% appreciation in housing prices—the highest appreciation of the largest 25 MSAs in the United States, as 22 of the top 25 MSAs saw a depreciation of housing values. Pittsburgh's story of economic regeneration was the inspiration of President Barack Obama to host the 2009 G-20 Pittsburgh summit. Geography Pittsburgh has an area of , of which is land and , or 4.75%, is water. The 80th meridian west passes directly through the city's downtown. The city is on the Allegheny Plateau, within the ecoregion of the Western Allegheny Plateau. The Downtown area (also known as the Golden Triangle) sits where the Allegheny River flows from the northeast and the Monongahela River from the southeast to form the Ohio River. The convergence is at Point State Park and is referred to as "the Point." The city extends east to include the Oakland and Shadyside sections, which are home to the University of Pittsburgh, Carnegie Mellon University, Chatham University, Carnegie Museum and Library, and many other educational, medical, and cultural institutions. The southern, western, and northern areas of the city are primarily residential. Many Pittsburgh neighborhoods are steeply sloped with two-lane roads. More than a quarter of neighborhood names make reference to "hills," "heights," or similar features. The steps of Pittsburgh consist of 800 sets of outdoor public stairways with 44,645 treads and 24,090 vertical feet. They include hundreds