CONFTDENT+L face varying restrictions on maximum evacuation distances. Boston, for example, is limited to about 20 miles of movement to the east, south, and west by the proximity of the seacoast and the Worcester, Providence, and Fall River targets, whereas Washington is relatively unlimited, being boundedfor all practical purposes only by the proximity of Baltimore and the coast. The proximity of other targets and physical barriers also set upper limits on the amount of dispersion that can take place. For example, although population density along the East Coast averages about 370 persons per square mile, many of the targets, limited by the afore-mentioned barriers, would still have concentrations many times that figure even if the population within the target could be evenly dispersed in the area allotted to it. New York, for example, would have concentrations of 2500 and Philadelphia 1500 persons per square mile, Evacuation Roads and the National Highway Program The feeling has been expressed by civil defense planners that the recently enacted public roads program would make mass evacuation possible or that the program could be modified to make such a tactic feasible.* Figure 12 shows the proposed highway system. It is clear that this 40,000-mile system is designed to connect majorcities and is not a system of radial routes emanating from congested urban areas into the surrounding countryside. It is not considered desirable to substitute radial routes for the intercity system. The latter routes were selected in cooperation with the military as being of first importance to the national defense, and are vital to the successful operation of plans for mutual aid in the postattack period that have been developed by the variouscities. It has been estimated that an expenditure of $10 billion is needed to provide for the evacuation of every person in the 23 largest target areas to beyond a 15-mile radius in 14 hr. An evacuation-highway program would in no way substantially reduce the requirement for a shelter program to protect evacuees from fallout, and the cost of the entire evacuation- highway-to-shelter program might be of the order of $18 billion. Should Congress consider a program to construct evacuation highways, the earliest year they could consider it would be 1957. Congressional action in 1957 would probably occur too late for enactment of cooperative state legislation that year so it would normally be carried over until the 1959 session. ‘If states were urged to call special sessions, state legislation could probably be speeded up by 1 yr. Regardless, it is evident that enactment of legislation affecting highways requires several years. Getting highway construction under way after legislation is enacted takes additional time. Routes must be selected, surveys made, land and property condemned, structures built, and pavements laid. This process normally takes at least 3 yr for each section of highway. By the time highway legislative and construction processes are completed and highWays are made available for evacuation, the us might well be into the intercontinental ballistic missile (1cBM) era. Feasibility In view of the probable short warning times of attack, the long times required for evacuation of targets, additional hazards that may further slow evacuation routes, the limitations on realistic practice of mass evacuations, dispersion limitations due to geographic *See, for example, the testimony of Governor Peterson in hearings before the Senate Committee on Armed Services." ORO-—R-17 (App B) 25