Canada's backlog of Nexus applications has ballooned into the hundreds of thousands, despite a sharp downturn in applicants during the pandemic.

The Canada Border Services Agency (CBSA) says 295,133 Nexus applications have yet to be processed due to ongoing office closures prompted by COVID-19.

Would-be cardholders in the program, which allows pre-approved Canadians to pass through separate, speedy lines when travelling to the United States, must be risk-assessed by both the CBSA and U.S. Customs and Border Protection.

The American agency reopened its Nexus enrolment centres for applicant interviews on April 19, but centres in Canada remain closed after shuttering in March 2020.

The resulting backlog means some Nexus members are struggling to book sit-downs before their cards expire, as Canadian residents hoping to renew their status can only schedule interviews in fewer than a dozen border community offices where slots are few.

The CBSA said in an email that Canada and the U.S. are in discussions about when to reopen Canadian enrolment centres.

"Although the extent of the backlog in 2019 is not known, I can tell you that the backlog has significantly increased over pre-pandemic levels due to the closing of the enrolment centres in March 2020 for public health reasons," spokeswoman Rebecca Purdy said.

Meanwhile the Fast program for cross-border commercial truck drivers now sports a backlog of 11,018, the CBSA said.

Jacques Roy, a professor of transport management at HEC Montréal business school, says the backlog is affecting business and leisure travellers. It also adds pressure to airports already struggling with security staff shortages and endless queues.

"I really am having a hard time understanding why nothing was was done or processed during that period," Roy said of the ongoing office closures.

The CBSA says it continues to carry out risk assessments remotely within its standard 30-day timeline for new applicants or those seeking to renew a soon-to-expire card.

However, once both countries have pre-approved the application, "the onus is then on the applicant to schedule an interview at a Nexus/Fast EC (enrolment centre) using the online portal," the agency said.

It has not set a date for when Canadian enrolment centres will unlock their doors.

This report by The Canadian Press was first published May 30, 2022.