Up to 3,200 passengers to be taken across Potomac on seven boats . Service is partially a response to the closure of all bridges from Virginia to Maryland Potomac Riverboat Association provides subsidies to the service . WASHINGTON ( CNN ) -- All passengers must be at least an hour early for a full screening .
Up to 3,200 passengers to be taken across Potomac on seven boats . Service is partially a response to the closure of all bridges from Virginia to Maryland Potomac Riverboat Association provides subsidies to the service . All passengers must be at least an hour early for a full screening .