City Council, at long last, has faced down one of the most arrogant, backwards and discriminatory institutions of the City of Philadelphia — the Building and Trades Council.

The Council is to be commended and Mayor-elect Michael Nutter, who stepped up to support the move by Council immediately, is also worthy of praise.

The vote to possibly open up the $700 million Convention Center expansion project to nonunion contractors could be, and hopefully is, the first step to breaking the decades old stranglehold that the racially-biased skilled labor unions have held in virtually excluding Blacks and Latinos.

Gov. Ed Rendell will also have to weigh in on this and the African-American community is listening intently with hands cupped to ears.

Excluding Local 332, the Laborers Union, which is predominantly Black and brown, the other 17 Building and Trades unions — by some estimates — are more than 90 percent white.

That trades council boss Pat Gillespie was unable to give Council an ethnic breakdown, even after being given 45 minutes via a recess in testimony to obtain the numbers from individual union presidents, is strong evidence that such estimates of white supremacy in the ranks is true.

The only reason for Gillespie not to reveal those numbers is embarrassment.

The ethnic breakdown of the skilled labor unions in this city has been guarded closer than top secret national security letters for over a half century.

There can only be one reason why.

Black contractors and qualified workers have told the Tribune numerous times over the years of resistance put forth by these unions when they tried to get work or join. There have also been instances where Blacks who did get in the union say they rarely get called to go out on a job.

One Black contractor told the Tribune recently he has been a union member for three years and hasn’t been put on a job by the unions since he joined.

At a time when unemployment of young Black men is high and the crime rate is being driven by the need of many of them to earn a living illegally, it is a bigger crime for the unions to continue to get fat piles of public money — much of it from Black taxpayers — while they discriminate against minorities.

It is way past time for these union to open their memberships and work sites to Blacks and Latinos or be denied public works revenue.