If Rod Blagojevich serves jail time, he will be the fourth Illinois governor since 1960 to be sent to prison on corruption charges. Why are officials from Illinois and its largest city, Chicago, so often shady?

Media playback is unsupported on your device Media caption Rod Blagojevich: "I've told the truth from the very beginning"

Political corruption and Chicago go together like fashion and Milan or surfers and Sydney: the association is deep, and it has shaped the city.

Most Illinois historians date the corruption back to 1869, when three county commissioners were convicted of fraudulently awarding a contract to paint City Hall with expensive long-lasting paint.

The contractor instead used whitewash, and split the handsome price difference with the three commissioners.

And then it rained. Suddenly the gleaming white City Hall didn't look so spiffy.

Judging by the Blagojevich trial, although he was convicted on only one of 24 charges, not all that much has changed in a century.

Founded on favours

Since 1970, there have been more than 1,500 convictions on public corruption charges in Illinois courts, according to Dick Simpson, a former Chicago alderman who currently heads the political science department at the University of Illinois, Chicago.

Image caption President Barack Obama's opponents have criticized his connections to "Chicago-style" politicians

"Everyone from Chicago aldermen and building inspectors to state governors has been involved," Mr Simpson told the BBC.

Cindy Canary, director for Illinois Campaign for Political Reform, says that the state was founded on favours.

The first wave of immigrants helped set up government and infrastructure, and soon encouraged their countryfolk to join them. They aided the newcomers, providing jobs and securing housing.

"As this state was settled, units of government were almost like social service agencies and over time that morphed into the modern political machine," Ms Canary told the BBC.

As elections unfolded in the state, the power of these ethnic voting blocks became evident.

Members of the Irish community voted for Irish candidates and were rewarded with jobs in the police force.

The Italian community voted for Italian candidates, who rewarded their own with jobs setting up Chicago's transit system, and so on.

'One party rule'

At the same time, cities and regions in Illinois developed monolithic party structures. Democrats had a vice-like grip on Chicago.

Convicted Illinois governors Rod Blagojevich (2003-09) for lying to FBI agents. Not yet sentenced, but faces maximum of 5 years in jail.

George Ryan (1999-2003) for corruption involving state licenses and contracts. Given 6.5 years in jail.

Daniel Walker (1973-77) for receiving fraudulent loans. Sentenced to 7 years in jail.

Otto Kerner Jnr (1961-68) for bribery, conspiracy and perjury. Given 3 years in jail.

"The culture of corruption from machine politics is helped by essentially one-party rule," Mr Simpson says.

"That sets in motion a problem where bribes and the like are more likely to flourish because the public officials can't tell the difference between what might be legal in campaigns and what is illegal when they seek money for public acts."

But in the early 1900s, such graft and patronage were not unique to Chicago. New York and Boston were similarly renowned as hotbeds of political corruption.

Yet those cities managed to clean up their act.

After decades of dominance, New York's enormously powerful Democratic machine, the infamous Tammany Hall, was finally routed by a combination of federal pressure from President Franklin D Roosevelt and reformist Mayor Fiorello La Guardia.

So why hasn't Chicago changed?

Lax finance laws

"That's the million dollar question that we ask ourselves all the time," Ms Canary says with a laugh.

Partly, the influence of the mob is to blame. With pivotal organised crime figures like Al Capone based in Chicago, the business of the mob and the business of government melded.

There is a sense that this state has been turned into a caricature of a state. That has offended people Cindy Canary, Director, Illinois Campaign for Political Reform

Ms Canary also says that waves of African-American migration from the American south played a role.

Growing African-American communities profoundly altered the power dynamics in cities like Boston and New York, but in Chicago, they were co-opted into the machine.

The African-American vote became critical to the success of politicians like long-serving Chicago Mayor Richard J Daley, a Democrat. (His son, Richard M Daley, became mayor in 1989.)

He was the founder of the so-called Daley machine, one of the most powerful political operations in the country in the latter part of the last century.

Mayor Daley is oft-credited with providing the necessary votes to secure President John F Kennedy's victory over Richard Nixon in 1960.

Ms Canary says another critical factor in her state's culture of corruption is the absence of strict campaign finance laws.

While federal elections are regulated by federal authorities, Illinois has some of the most relaxed regulations for state and local campaign finance in the country.

The vast majority of Illinois officials involved in corruption cases are state and local politicians, not federal ones.

Unlikely poster child

The unique power of Chicago's mayor also has an impact on corruption. By far the largest city in the state, the mayor of this densely packed metropolis and economic powerhouse wields might almost equivalent to that of the state's governor.

Attempts by one to reform the state's murky ways are easily thwarted by the other.

Mr Simpson notes that although there have been a few reformist mayors - like Edward Dunne or William Dever - they rarely survive re-election.

Image caption Rod Blagojevich has denied any wrongdoing and intends to appeal against his conviction

More recently, reform-oriented Mayor Harold Washington made inroads, but died after just four years in office.

"That simply wasn't a long enough period to put in all the barriers to corruption that would be necessary and to get the public to expect a non-corrupt government," Mr Simpson said.

Perhaps unexpectedly, Rod Blagojevich - who himself won office on a pro-reform agenda - has become the unwitting poster child for the need to clean up Illinois politics.

Ms Canary says that for a long time Chicago-style wheeling and dealing was "a very perverse source of pride - you know, our elected officials are bigger rascals than your elected officials".

Chicagoans privately relished their sordid mob history and its dramatic depictions in films like The Untouchables.

But the media circus surrounding the Blagojevich trial, including the reality TV shows that Blagojevich and his wife appeared in and the widely-played tapes of his alleged deal-making, have been a turn-off for voters.

"There is a sense that this state has been turned into a caricature of a state. That has offended people," Ms Canary says.

"Slowly people are starting to understand that this comes with a cost. They aren't just funny stories, although some of them are hilarious."

The Blagojevich trial provided new momentum to advocates for stricter regulation and transparency in Illinois politics.

And they have had some success: new campaign finance laws, the strictest in Illinois history, will be enacted in January 2011.