One of the bigger surprises of business in the year 2009 was how big of a hit U.S. e-commerce has taken. According to digital marketing intelligence firm comScore in its just-released report 2009 U.S. Digital Year in Review, e-retail spending in America decreased about 2% during the year to come in just under $210 billion.

This represents the first decline in e-commerce spending ever recorded.

Obviously, the economic recession was the culprit. But considering that e-commerce growth has charted above 20% annually in every year leading up to 2009, seeing an actual fall-off has raised more than a few eyebrows.

Where was the e-commerce decline most pronounced? It was in travel-related services, which saw revenues drop by 5% to ~$80 million. Not that all sectors saw decline. A few continued to experience growth during the year, including the books/magazines category which charted gains of ~12%. Online computer software purchases were also up by about 7%.

What does comScore see on the horizon for U.S. e-commerce? Is continued softness predicted … or a return to robust growth?

Analyzing the last few months of e-commerce activity during 2009 provides clues to the future: Growth looks like it’s returning. In fact, the 2009 holiday season marked a return to positive growth rates when compared against the same period in 2008.

[Granted, this comparison is made against “down” months of November and December in 2008, after the recession had already kicked in. But the pace of e-commerce activity is clearly picking up again.]

But whether it will go back to a 20%+ annual growth is still an open question.