This chart and map track recent movements in single-family home sales in Howard and Carroll counties by ZIP code. The chart lists sales volume and median price for November 1991, the most recent month available, and compares those figures with 1990 statistics.

In future weeks, charts and maps will appear for:

* Harford County, Feb. 16.

* Anne Arundel County, Feb. 23. (Anne Arundel information, scheduled to appear today, has been delayed.)

* Baltimore and Baltimore County, March 1.

The next metro-wide roundup of sales activity will appear in late March.

The information is provided by Rufus S. Lusk & Son Inc.