According to the latest MusicWatch consumer surveys from The NPD Group, Apple is again the top music retailer in the US.

The five leading music retailers in the U.S. for the first half of 2008 (January through June, based on purchases of CDs and a-la-carte digital music downloads) are:

1. iTunes
2. Wal-Mart (Walmart, Walmart.com, Walmart Music Downloads)
3. Best Buy (Best Buy, Bestbuy.com, Best Buy Digital Music Store)
4. Amazon (Amazon.com, AmazonMP3.com)
5. Target (Target and Target.com)

NPD’s data reflects the ongoing consumer shift from physical CDs to digital music, as iTunes maintained their leadership position reached earlier this year. Amazon rose from fifth place to fourth primarily for two reasons: first, online CD sales have seen less erosion than CD sales at brick-and-mortar stores; and second, Amazon launched its digital music store, Amazon.mp3, last year.

“We expect Apple will consolidate its lead in the retail music market, as CD sales continue to slow,” said Russ Crupnick, entertainment industry analyst for The NPD Group. “Amazon’s CD buyers tend to be older, so they haven’t abandoned the CD format to the extent seen in the average music buyer. Plus Amazon’s successful introduction of its digital download store will help the company improve its position in the future.”