From the Colorado Division of Housing on Feb. 2, 2012:
According to new metro Denver vacancy and rent data for 2011's fourth quarter, released this week by the Colorado Division of Housing, multifamily rental vacancies fell again while median and average rents increased slightly.
The region-wide vacancy rate in metro Denver has fallen every quarter for the past nine quarters when compared to the same quarter a year prior. As can be seen in the first graph, the year-over-year change in vacancies has not been positive since the third quarter of 2009, when the vacancy rate rose 13.8 percent over the year prior.
When comparing all county areas in the metro Denver area, we find that the Boulder/Broomfield area has consistently reported some of the lowest vacancy rates in recent quarters.
Although the Boulder/Broomfield area tends to have some of the lowest vacancy rates, rent growth in that area has produced frictional vacancy, in which tenants are beginning to move out and look for new apartments in response to a large amount of growth in rents. In other words, once vacancies reach very low levels, property managers will begun to push rents, and as this happens, vacancies move up as a result of increased tenant relocation.