For most of Philadelphia's history, the tense, delicate balance (and imbalance) between black and white has shaped and defined the city.

Political power, economic conditions, the city's unique culture; all of it has flowed from the interplay between these two Philadelphias.

But it's not that simple anymore. The latest census figures - which say 21 percent of city residents are now neither white nor African American - make it foolish to view Philadelphia through the binary racial prism of the past.

"This city is no longer black and white," said Angel Ortiz, a former City Councilman and a Puerto Rican activist.

Somehow this essential development has been overlooked in recent stories about continued white flight and the emergence of African Americans as the largest ethnic group in the city.

The fact is that explosive growth in the city's Latino and Asian populations is the main reason Philadelphia expanded in the 2000s instead of shrinking for a sixth straight decade.

Latino, Asian, and other populations have swelled by 183,000 since 1990, even as the white and black totals declined 243,000, as detailed in a Pew Charitable Trusts study last week.

This is no surprise to anyone who lives in Philadelphia. The city's changing identity is obvious on the streets, and not just in long-established enclaves like Chinatown and the North Fifth Street corridor. There are the growing Mexican, Cambodian, and Vietnamese communities in South Philadelphia, Brazilians in Oxford Circle, Korean immigrants in Olney, and so on.

All of which is fantastic for Philadelphia.

Immigration means vitality, commerce, and growth. It means more languages on the bus, more interesting food in city restaurants, new artistic and cultural expressions. More, in other words, of everything that makes American cities what they are.

But these momentous demographic changes have not registered with the city's hidebound political system, where Latinos and Asians have been almost entirely shut out.

There are no Asians on City Council. No ward leaders. No Council members. No state legislators.

Latinos - now at least 12 percent of the city's population - fare little better. State Rep. Angel Cruz is not just Philadelphia's sole Hispanic representative in Harrisburg, he is the only elected Latino in the 253-member legislature. Maria Quiñones Sánchez is the only elected Latino on Council; only three of 64 Democratic ward leaders are Hispanic.

"I don't think the power structure in either the black or the white community gets it," said Ortiz, who was the first Hispanic elected to Council, serving between 1992 and 2000. "I don't think they realize this is a problem."

But it is a problem. It's a problem when our elected officials do not reflect the city they represent, and it's a problem (albeit a predictable one) when the political establishment works to thwart the aspirations of increasingly large and important segments of the city.

"There needs to be a greater acknowledgment that these are groups that really contribute to our city, that these groups are growing, and that if we want our city to continue growing, we need to encourage that," said Andy Toy, an Asian American who ran a strong race for an at-large Council seat this spring.

The political machinery, though, has more often worked to discourage participation than encourage it.

Take the Seventh Council district, which Sánchez represents. This preposterously drawn district veers erratically across North Philadelphia and the Lower Northeast.

Only it's not erratic at all. It was designed, very carefully, by Council. It was drawn to protect then-incumbent Rick Mariano (pre-prison term) by carefully excluding Latinos and looping in whites from the Lower Northeast.

U.S. Rep. Bob Brady acknowledges his party should do more to welcome Latinos and Asians. And he said he would support a redistricting plan that would make the Seventh District more solidly Latino.

But Brady contends that these new Philadelphians need to become more engaged if they expect to get a piece of the political pie.

"A lot of them aren't registered. A lot of them aren't active. If you don't vote, you don't count," Brady said.

That looks to be changing. Republican David Oh has a real chance to become the first Asian on Council this fall. And it is telling that last month, Sánchez won renomination over a ward leader-backed white challenger in the Seventh District despite the gerrymandering.

"The census numbers are giving us a push. They really clarify the underrepresentation of our people in the halls of power, which can no longer be tolerated," Ortiz said. "It's time to challenge the status quo."

Patrick Kerkstra is a former Inquirer City Hall reporter. Contact him at Patrick@PatrickKerkstra.com or follow him on Twitter @pkerkstra