Though rental markets around the country are experiencing rising demand, not all landlords are watching their vacancy rates shrink.

Property managers in New Orleans appear to be having the hardest time getting tenants to sign lease agreements. The latest Census Bureau data from the American Community Survey showed that New Orleans' vancancy rate – for both rental and single-family homes – stands at 21.5 percent, the worst rate of the 81 U.S. cities with at least 100,000 homes, reported Buffalo Business First. St. Louis posted the next-highest vacancy rate – 19.35 percent – while Detroit came in third, posting a rate of 18.33 percent.

On the other hand, San Jose, California, enjoyed the best vacancy rate among cities with at least 100,000 residents, with 3.3 percent of all that city's housing vacant.

The report also showed that landlords in Buffalo, New York, are dealing with the nation's oldest stock of housing. More than 87 percent of dwellings in the city were built over 50 years ago, said the paper. Detroit came in second at 84.1 percent, and only two other cities topped 80 percent – Cleveland and St. Louis.

The issue of aging housing has troubled landlords and communities around the country, with Multi-Housing News reporting that many affordable housing projects will soon lose the restrictions which preserve units for low-income tenants.