A gaping 20-foot-wide hole in the 300 block of Canal Street — which provided instant fodder for amateur comedians and was honored at an impromptu “Sinkhole de Mayo” celebration on May 5 — has been repaired months ahead of schedule at a cost of at least $3 million.

Mayor Mitch Landrieu reopened the section of Canal Street between Canal Place and Harrah’s Casino on Tuesday afternoon. The street had been blocked off since late April.

“With a sense of urgency, our City Council partners issued an emergency declaration, our contractor got to work, and the repair was completed on task, on time and under budget,” Landrieu said.

The street actually was closed two weeks before the hole emerged after engineers noticed a collapsing section of the wall of a 50-year-old underground tunnel that was once envisioned as part of a riverfront expressway.

The hole appeared about 3:30 p.m. April 29. Asphalt buckled and fell into the deep cavern, and the nearby neutral ground cracked and was at risk of collapsing as well.

The City Council gave the greenlight to fix the problem on an emergency basis on May 5, and repairs began a day later.

Officials originally said the problem apparently started when water from a drainage line began leaking onto the steel-reinforced wooden wall that was built in the 1960s as a “temporary” closure to the tunnel, originally intended to be part of the controversial French Quarter riverfront expressway that was killed in 1969.

However, officials later said the exact cause of the collapse was unclear. Rain also may have played a role, they said.

Landrieu has said the problem apparently started when water from a drainage line began leaking onto the steel-reinforced wooden wall that was built in the 1960s as a “temporary” closure to the tunnel, originally intended to be part of the controversial French Quarter riverfront expressway that was killed in 1969.

However, officials later said that the exact cause of the collapse was unclear. Rain may have also played a role, they said.

The gigantic sinkhole was estimated to cost between $3 and $5 million to repair, with the job taking between three and six months, though officials said the opening itself might be closed before then. The city said Tuesday that repairs, which began on May 6, stayed within its $5 million budget.

Filling the huge hole initially was projected to take between three and six months, though officials said the opening itself might be closed before then. Instead, it took less than seven weeks to repair, the city said.

Contractors had to install a permanent concrete replacement for the underground wall, replace drainage lines ruptured in the collapse and fill the hole that was left behind with three layers of concrete. All the while, they had to dodge the nearby streetcar line and avoid damage to other utilities.

The cost of the repairs is still being calculated, but officials expect the bill to come in at more than $3 million, which is at the low end of the original estimate of $3 million to $5 million.

Harrah’s, which uses a portion of the underground tunnel, soon will meet with the city to figure out how to divide the costs.

Consulting firm Hatch Mott MacDonald handled design, engineering and management services on the project for $700,000, while Eustis Engineering LLC provided geotechnical assistance for another $100,000. Both firms oversaw the work done by Hard Rock Construction, one of three firms the city asked to submit bids for the emergency project.

As the city worked to enclose the hole, many local residents, long used to crumbling streets, made light of the whole affair through social media and an impromptu “Sinkhole de Mayo” party at nearby Woldenberg Park that drew several hundred people.

The event started out as bar crawl among friends but blossomed when it was posted to Facebook, eventually getting 1,700 RSVPs.