Hello, can you tell me about the history of the United States. 
 The $18 trillion U.S. economy relies on a vast network of infrastructure from roads and bridges to freight rail and ports to electrical grids and internet provision. But the systems currently in place were built decades ago, and economists say that delays and rising maintenance costs are holding economic performance back. 
 Cool, can you tell me any fun facts about the United States? 
 Interesting, can you tell me more about the history? 
 Very informative, can you tel me about the infrastructure?
The $18 trillion U.S. economy relies on a vast network of infrastructure from roads and bridges to freight rail and ports to electrical grids and internet provision. But the systems currently in place were built decades ago, and economists say that delays and rising maintenance costs are holding economic performance back.