Valley that once served as backbones for the region's economy suffered similarly, either downsizing significantly or dissolving, which destabilized the region considerably. In the early 2000s, seeking to replace the heavy manufacturing companies that had been the region's foundation for decades, the Lehigh Valley began developing other economic sectors, including financial services, health care, life sciences, and technology. The Lehigh Valley also began emerging as a national warehouse and distribution hub, largely due to its proximity to many of the largest U.S. markets and relatively lower operating costs compared to other Northeast U.S. regions. More recently, a movement to reestablish manufacturing activities in the U.S., driven by customer demand for American-made products, faster product delivery, increased overseas wages, and inflated costs and extended timeframes for shipping has led to some renewed growth in the Valley's manufacturing sector. Several large companies from China and Germany have invested tens of millions of dollars into developing significant operations in the Lehigh Valley, which has generated thousands of new jobs in the region. Largest employers As of 2019, the Lehigh Valley's top five employers are: 1.) Lehigh Valley Health Network, 2.) St. Luke's Hospital and Health Network, 3.) Amazon, 4.) Lehigh Valley Physician Group, and 5.) Mack Trucks. Business and economic environment The Lehigh Valley is one of the fastest-growing and largest economies in Pennsylvania with a total GDP of $43.8 billion that saw a five percent increase between 2016 and 2017 alone driven by strong manufacturing, financial, health care, and professional services industry segments. It is centrally located in the Northeast megalopolis with ease of access and close proximity to several of the largest U.S. markets, population centers, airports, terminals, railways, and seaports, including the New York City and Philadelphia metropolitan areas. The Lehigh Valley is within a one-day drive to over a third of the U.S. population and to over half the population of Canada. The Valley has a lower cost of living, more affordable real estate, lower taxes, and a larger and more affordable labor pool than many other Northeastern U.S. metropolitan regions. These attributes and others, including sizable investments in business development incentive programs and a friendlier regulatory environment, provide the area with a comparatively favorable business climate compared to surrounding metropolitan areas. Due in large part to this comparably favorable business climate and mature business support programs, the Lehigh Valley has been very successful in luring established businesses as