Rental vacancy rates fell from 8.4 percent to 7.4 percent in two years, the American Community Survey stated.
Vacancy rates dropped while the share of U.S. households "that rent rather than own" a home increased from 34.1 percent to 35.4 percent.
The survey also found that "more renters are spending a high percentage of their household income on rent."
"In this report, renters spending 35 percent or more of household income on rent and utilities are considered to have high rental costs," the Census Bureau said.
And that percentage rose. In 2009, 42.5 percent of renters were considered to be categorically paying high housing costs. By 2011, that had grown to 44.3 percent, the report said.
"While we saw a decrease in rental vacancy rates and pricing in some areas, the burden of rental costs on households increased across many parts of the nation," said Arthur Cresce, assistant division chief for housing characteristics at the Census Bureau in a statement.
"Factors such as supply and demand for rental housing and local economic conditions play an important role in helping to explain these relationships," Cresce said.