WASHINGTON — Construction activity in October plunged by the largest amount since the recession in 2001 as home building fell for a record seventh consecutive month.

The Commerce Department reported yesterday building activity dropped 1 percent to a seasonally adjusted annual rate of $1.18 trillion in October after a 0.8 percent fall in September. It was the biggest decline since a similar 1 percent drop in September 2001, when the country was hit by the terrorist attacks as it was mired in a recession.

Residential construction fell for a seventh month in October, the longest stretch of weakness on record. The 1.9 percent drop in this category in October was the biggest decline since July.

The weakness in housing was compounded by a drop in nonresidential construction, which fell by 0.7 percent, the second straight decline in this category.

Only government construction activity showed strength in October, rising by 0.8 percent to an all-time high of $273.1 billion at an annual rate.

The new report served to underscore the significant reversal in the fortunes of the housing industry, which had been one of the economy's standout performers as the lowest mortgage rates in four decades pushed sales up to record highs for five straight years.

Builders have been offering a host of incentives from kitchen upgrades to free swimming pools to move a record backlog of unsold homes.

The government reported this week that the slowdown in housing trimmed 1.16 percentage point from economic growth in the July-September quarter, a period when the economy slowed to a growth rate of 2.2 percent.