	Introduction

Critical infrastructure is so vital to the United States that its incapacity would harm the nation's physical security, economic security, or public health. When infrastructure is physically concentrated in a limited geographic area it may be particularly vulnerable to geographic hazards such as natural disasters, epidemics, and certain kinds of terrorist attacks. In 2005, Hurricanes Katrina and Rita demonstrated this kind of geographic impact by disrupting a substantial part of the national U.S. energy and chemical sectors, both heavily concentrated in the Gulf of Mexico. 109-58 ) facilitated the construction of new liquefied natural gas import terminals in diverse ports by granting the Federal Energy Regulatory Commission exclusive siting approval authority (Section 311). Provisions in the Pipeline Safety Improvement Act of 2006 ( P.L. 109-468 ) require periodic studies to identify geographic areas in the United States where unplanned loss of oil pipeline facilities may cause oil shortages or price disruptions (Sec. The 110 th Congress is overseeing implementation of these measures and considering additional policies which may affect critical infrastructure concentration. Prominent among these are legislative proposals such as H.R. 6566 , H.R. 6709 , S. 3202 , and S. 3126 , which would lift federal moratoriums on, or otherwise encourage, offshore oil and natural gas development outside the western Gulf of Mexico. It reviews several ways in which the federal government has also influenced critical infrastructure, such as prescriptive siting, economic incentives, environmental regulation, and economic regulation. They have developed for multiple reasons—typically some combination of market influences, including resource location, agglomeration economies, scale economies, community preferences, and capital efficiency. These influences often have been in place for decades, gradually driving critical infrastructure development to its geographic configuration today. Federal Policies and Infrastructure Concentration

Although market forces have been the primary influence on critical infrastructure development, especially in the private sector, Congress and federal agencies historically have, from time to time, adopted policies intended to affect the capacity and location of critical infrastructure in the national interest. More recently, the Energy Policy Act of 2005 ( P.L. Some analysts may argue that little government intervention in infrastructure concentration is necessary because the private sector will appropriately adjust its infrastructure practices out of its own financial interest. If Congress concludes that more federal intervention is needed to alleviate vulnerabilities due to geographic concentration, it may employ a number of policy options to encourage geographic dispersion (including eliminating policies that encourage concentration ), ensure survivability, or ensure that effective infrastructure recovery capabilities are in place to mitigate impacts of concentrated infrastructure disruption. Because geographic hazards exist today, and geographic dispersion would likely take decades to achieve, addressing geographic vulnerabilities may call for a combination of options. As Congress evaluates diverse proposals with the potential to affect critical infrastructure development—directly or indirectly—Congress may consider whether such proposals are likely to relieve or exacerbate geographic vulnerability. Fiscal implications, especially related to the economic efficiency of public critical infrastructure and the efficient use of federal funds for infrastructure projects, may also be an important consideration.
"Critical infrastructure" consists of systems and assets so vital to the United States that their incapacity would harm the nation's physical security, economic security, or public health. Critical infrastructure is often geographically concentrated, so it may be distinctly vulnerable to events like natural disasters, epidemics, and certain kinds of terrorist attacks. Disruption of concentrated infrastructure could have greatly disproportionate effects, with costs potentially running into billions of dollars and spreading far beyond the immediate area of disturbance. Hurricane Katrina in 2005, and Hurricane Ivan in 2008, have demonstrated this kind of geographic vulnerability by disrupting much of the U.S. energy and chemical sectors.
Congress has been examining federal policies related to the geographic concentration and vulnerability of critical infrastructure. In the 109th Congress, the Energy Policy Act of 2005 (P.L. 109-58) facilitated the construction of new liquefied natural gas import terminals in diverse ports. Provisions in the Pipeline Safety Improvement Act of 2006 (P.L. 109-468) require studies to identify geographic areas in the United States where unplanned loss of oil pipeline facilities may cause oil shortages or price disruptions. The 110th Congress is considering additional policies which may affect critical infrastructure concentration. Prominent among these are legislative proposals such as H.R. 6566, H.R. 6709, S. 3202, and S. 3126, which would lift federal moratoriums on, or otherwise encourage, offshore oil and natural gas development outside the western Gulf of Mexico.
Geographic concentrations of U.S. critical infrastructure typically have developed through some combination of market influences, including resource location, agglomeration economies, scale economies, community preferences, and capital efficiency. Congress and federal agencies also have adopted policies affecting the capacity and location of critical infrastructure, including prescriptive siting, economic incentives, environmental regulation, and economic regulation. Some federal policies have been developed specifically to address perceived threats to critical infrastructure. These influences often have been in place for decades, gradually driving critical infrastructure to its geographic configuration today.
Some analysts may argue that little government intervention is necessary to alleviate geographic vulnerabilities of critical infrastructure because the private sector will adjust its practices out of its own financial interest. However, if Congress concludes that federal intervention is needed, it may employ a number of policy options to encourage geographic dispersion (including eliminating policies that encourage concentration ), ensure survivability, or ensure that effective infrastructure recovery capabilities are in place to mitigate impacts of concentrated infrastructure disruption. Addressing geographic vulnerabilities may call for a combination of options. Congress may also consider whether other legislative proposals with the potential to affect critical infrastructure development—directly or indirectly—are likely to relieve or exacerbate geographic vulnerability. The economic efficiency of public critical infrastructure and the efficient use of federal funds for infrastructure development may also be important considerations.