Public capital is the aggregate body of government-owned assets that are used as a means for private productivity. Such assets span a wide range including: large components such as highways, airports, roads, transit systems, and railways; local, municipal components such as public education, public hospitals, police and fire protection, prisons, and courts; and critical components including water and sewer systems, public electric and gas utilities, and telecommunications. Often, public capital is defined as government outlay, in terms of money, and as physical stock, in terms of infrastructure.
In 1988, the U.S. infrastructure system including all public and private non-residential capital stock was valued at $7 trillion, an immense portfolio to operate and manage. And according to the Congressional Budget Office, in 2004 the U.S. invested $400 billion in infrastructure capital across federal, state, and local levels including the private sectors on transportation networks, schools, highways, water systems, energy, and telecommunications services. While public spending on infrastructure grew by 1.7% annually between 1956 and 2004, it has remained constant as a share of GDP since early 1980s. Despite the value and investment of public capital, growing delays in air and surface transportation, aging electric grid, an untapped renewable energy sector, and inadequate school facilities all have justified additional funding in public capital investment.