There is alot to like in the recently announced 5.7% rate of US GDP growth in the fourth quarter of 2009. 

While many commentators are brushing it off as a fluke tied to the vagaries of inventory trends, it is actually very normal for inventory swings to account for a good portion of GDP growth when the cycle is first turning.  The question is always whether growth can then get handed off to sustained consumption and private investment after a few quarters.  I think it can, but extreme swings in public policy could theoretically jeapordize the expansion.

The personal consumption number is encouraging, particularly given that consumer credit has been declining.  This implies that we are moving to a sustainable level of spending, complemented by a positive savings rate.  Government transfer payments tied to unemployment insurance and the stimulus package are supporting spending, of course, and my advice would be to withdraw this support only gradually in 2010, if at all.

Net Exports were actually weaker than the real GDP figures reported.  In nominal terms, the trade deficit actually widened as a percent of GDP in Q4.  Petroleum imports increased in nominal terms, but because of rising prices, fell in real terms.  On the flip side, exports grew 25% in nominal terms, meaning world trade is on the rebound and the US can benefit from a strong rebound in the manufacturing and service sectors if it can borrow excess demand from abroad.  Because both the domestic demand and supply of credit is limited, there is reason to be optomistic that exports should expand faster than imports if the dollar stabilizes at current levels.  From a purely economic point of view, it would make sense for the US tom implement policies to reduce its demand for imported oil (to go along with the environmental and security reasons to do so.)  In fact, virtually the entire trade deficit can be traced to the petroleum and auto sectors.

An increase in business investment, on the other hand, was limited purely to high tech equipment.  Traditional industrial and transportation equipment investment remains in the cellar.  There is good reason to expect investment in transportation equipment to rebound from the currently depressed levels not seen since the 1970s in real terms.  Industry, however, suffers from huge levels of excess capacity.  Many sectors of manufacturing got hammered as a whole in the downturn, and had only been skating sideways at best during the expansion of the 2000s.  The most successful manufacturing sectors in the 2000s were high tech, med tech and defense / aerospace which should all continue to thrive, in addition to housing related sectors like wood products, non-metallic minerals, furniture, appliances and fabricated metal products which are highly unlikely to thrive in the intermediate term.  Much of the rebound in manufacturing to date (again, outside of high tech) has been limited to cars, chemicals and steel bouncing from extremely depressed levels to just merely depressed.

Residential real estate investment has clearly bottomed and has added modestly to GDP in the last two quarters.  As a percent of GDP, however, it is at the lowest level since World War II.  Commercial real estate investment continues to plunge, which can be expected for another couple of quarters before bottoming out at record low levels of GDP as well.  Credit conditions, slowing demographics and recent over-investment will all conspire to keep real estate investment at record low levels for at least the intermediate term.

The huge excess capacity in construction workers and construction-related manufacturing leads me to continue to stress how beneficial it would be to focus additional stimulus on infrastructure spending.  These workers can not easily be retrained for health care, education and high tech office jobs.  The country has been behind on such spending anyway, so it would not be Japan-style "bridge-to-nowhere" investment as long as Congress can be reined in.  For this reason I like the "infrastructure bank" idea that takes some of the planning out of the hands of Congressional pork-meisters.

US Indebtedness as a percentage of GDP actually declined in Q3 from 359% to 355%, due primarily to a decline in financial sector debt.  Household and business debt each declined in Q3 as well, but were offset by an increase in US government debt, which increased to 53%, up from 36% at the start of the recession.  In general, I expect this trend continued in Q4 as well, as the US offsets private deleveraging with public borrowing.

In conclusion, the strong parts of the economy (high tech, aerospace, health care and education) are now in expansion mode, and the extractive industries (farming, mining, energy) are likely to join soon.  Those manufacturing sectors exposed to export markets like industrial equipment (think Caterpillar) should resume growth as well unless there is a major economic crisis in the emerging markets.   "Old economy" manufacturing and real estate investment remain a problem and are likely to remain so without increased infrastructure investment.  The trick for policy makers is to transition from a period of broad stimulus to one of consumer and government belt-tightening while letting business investment, infrastructure spending and exports become the primary economic growth drivers.  It would be a neat trick, indeed.