The hypocenters of about 300 well-recorded earthquakes in mainland Alaska, the Alaska Peninsula, and adjacent offshore areas that occurred during the 10-year period before the Alaska earthquake of March 28, 1964, were relocated using an iterative least-squares method. Most of the corresponding epicenters were located with a precision of about 10 to 20 km. In previous studies of this region errors as large as 100 km were common. Since a large number of events can now be located with a greater precision, many of these epicenters can be related to major geologic and tectonic features. A narrow zone of intermediate-depth earthquakes extends from the Alaska Peninsula to the northern boundary of the Alaska Range province in central Alaska. More intermediate-depth earthquakes occur in this region than in any other part of the United States. The volcanoes of the Aleutian Range fall within the zone of epicenters of the intermediate-depth events. These earthquakes, however, extend about 250 km beyond the northern limits of present volcanism. Similarly, a belt of shallow earthquakes can be traced from the Alaska Peninsula and adjacent offshore areas to central Alaska. This latter belt has a greater areal extent than the zone of intermediate-depth earthquakes. Much of the region that was associated with the aftershocks of the 1964 Alaska earthquake exhibited only minor seismicity during the 10-year period before March 28, 1964. Hence, very little strain energy was released in this part of the aftershock region during the 10-year interval of this study. The epicenters of several shallow earthquakes occur on or close to the Denali, Castle Mountain, and Chugach-St. Elias fault zones. Most of the epicenters of shallow earthquakes, however, are not associated with known faults. Also, several major faults did not exhibit observable seismicity during this 10-year period.