In the Nov. 2006 issue of Insight to IBOC, we provided a nationwide overview of the HD Radio rollout. At the time, there were about 1,013 stations transmitting an HD Radio signal. In the nearly 18 months since then, approximately 600 stations have commenced HD Radio transmissions.

In Nov. 2006, four states had no HD Radio stations on the air: Hawaii, North Dakota, South Dakota and Alabama. We also had no data on Puerto Rico, so it's likely there weren't any stations on the air there. Now, every state and commonwealth has at least one HD Radio station on the air.

As of March 31, 2008, Ibiquity reports that there are 1,657 stations transmitting an HD Radio signal.

Also in Nov. 2006, the top four HD Radio adoption states were California with 109 stations, Texas with 74 stations, New York with 68 stations and Florida with 63 stations. Today, those ranks are almost the same with Florida and New York swapping positions. The station totals have increased to California with 162 stations, Texas with 121 stations, Florida with 112 stations and New York with 96 stations.

The steady HD Radio adoption continues, although it seems to have slowed somewhat. This can be attributed to many factors, but one likely reason is that the first stations were the simplest to upgrade or were in the largest markets where it made the most sense.

As of March 31, 2008, Ibiquity reports that there are 1,657 stations transmitting an HD Radio signal.