Now this is strange...
... a document from 05/28/1855 in St. Clair County, IL for a mulatto "servant" named Abraham Kinney grants him his emancipation upon turning age 21. Remarks on the page however indicate he was "born free," or so to speak. 21 years is definately greater than 1 year, non-seq, and poor Mr. Kinney spent his first two decades of life as a servant of a Mr. John Thomas before being emancipated.
Here's another one. Mulatto "servant" James W. George was emancipated at age 12 on 04/05/1855. His former master, John O. Pierce, stated himself to have known the company of Young Mr. James "FOR ABOUT 12 YEARS." 12 years is also greater than a year, non-seq.
Here's another one from 10/02/1850 for Ishaw, described as "a negroe" age 27. He was determined emancipated on that day on the grounds that "HE CAME OF AGE SIX YEARS AGO" - meaning he spent the first 21 years of his life as John Reynolds' slave...er..."servant" in Illinois
Seems as if your "slave, but only for a year" provision wasn't practiced very much, non-seq.
I'm not surprised, given you don't seem to have bothered to even read the Black Codes that you condemn so strenuously. Under the original laws, male children born to indentured servent were indentured themselves until they were 35. That was modified to age 21 when the first state constitution was ratified in 1818. A year later the Black Codes mandated that new indentures were limited to a year only. All of which combine to show your claim and that of 4CJ that new indentures as late as the 1860's were for 99 years or some such ridiculous figure.
In 1828 the Illinois Supreme Court ruled on the 1807 Indenture law, calling it an abomination and voiding the law. However, since the state constitution had protected indentures made under that law in Article 6, Setion 3, the court felt that they could not void those indentures. So they continued to their end.
The Black Codes in Illinois were not unique in the U.S. and I agree with the Supreme Court ruling that they were repugnant to the ordinance of 1878 and should never have been enacted in the first place. They were a blot on the history of that great state, but a part of our history that cannot be denied or explained away. But that is where we part company, it seems. I think that all Black Codes were abominations and you seem to have a problem with only the Northern ones. I accept that the North has nobody but themselves to blame for their racist policies, and you blame the North for yours. Total denial on your part.