Most deadly tornado:

The tri-state tornado that raked Missouri, Illinois, and Indiana on March 18,1925, killing 689 persons and injuring over 2,000 along a path of more than 200 miles.

Largest number of tornadoes to occur simultaneously:

The so-called Super Outbreak of 1974, in which 148 tornadoes were reported in 13 states and Canada between noon, April 3, and seven o’clock the following morning. The death toll reached 315, and damage was estimated at more than $600,000,000.

Length of track:

Commonly less than 10 miles, although a single tornado in 1947 careered 221 miles from Texas through northwest Oklahoma into Kansas.

Width on the ground:

From a few yards to more than 2 miles; average less than one-quarter mile.

Wind speed:

In the vortex itself, unknown, but believed never to exceed 300 miles per hour and rarely 200. Forward speed on the ground averages some 45 m.p.h., although the great tristate tornado achieved a progress of 70 m.p.h. shortly before dissipating near Princeton, Indiana.

Means of survival:

Since most tornado deaths result from flying debris or collapsing structures, safest refuge is found against the west wall of a soundly constructed basement. In buildings without basements, a small central bathroom, closet, or hallway on the ground floor may afford protection. In the open, cover should be sought in a ditch or other depression.