The city’s rental vacancy rate fell to its lowest level since 1968.

New York City’s housing market is the tightest it’s been in more than five decades, with just 1.4 percent of rental apartments vacant and available, a new survey found.

The citywide vacancy rate stands at its lowest since 1968, qualifying as a certified “housing emergency.” The report offers a striking illustration of the shortage: Residential construction has failed to keep pace with demand and low-cost homes in particular have become exceedingly scarce, threatening the ability of financially struggling residents to live in the nation’s largest city, according to the findings from the city’s housing agency.

As a result, lower-income New Yorkers are spending more of their paychecks on rent. Among households earning less than $25,000 per year without rental assistance, 86 percent were severely rent-burdened — defined as paying more than half of one’s income on rent. The survey also found an “alarming increase” in missed payments and arrears.