Currently under Chicago law in the State of Illinois, it is appears to be illegal to possess air guns or airsoft guns as stated here in CHAPTER 4-144 WEAPONS DEALERS, more specifically: ARTICLE III. AIR RIFLES AND TOY WEAPON DEALERS(4-144-140 seq.): 

4-144-145  Replica air guns – Sale or transfer prohibited.
 
   (a)   It shall be unlawful for any person to engage in the business of selling or to sell, exhibit for sale, give away or otherwise transfer any replica air gun in the city of Chicago. For purposes of this article, “replica air gun” means and includes any air gun, air pistol, air rifle, spring gun, spring pistol, BB gun, pellet gun or any other implement that a person could reasonably perceive as an actual firearm but that is not a firearm, and that is capable of firing or discharging a projectile constructed of hard plastic, steel, lead or other hard materials with a force that reasonably is expected to cause bodily harm.

However, this only mentions that replica air guns being transfered to other people in the city limits is illegal, but possessing one appears to be not if you look closely at this section of the chapter:

4-144-190  Replica firearms and pellet guns.
 
   (a)   It shall be unlawful for any person to purchase, possess, conceal, use, sell, give away or otherwise transfer, or to engage in the business of selling or to exhibit for sale, a replica firearm, paint pellet or paint pellet gun in the City of Chicago, except as provided in subsection (c) of this section.
 
   (b)   For the purposes of this chapter, the following terms shall have the following meanings:
 
      “Paint pellet” means a pellet or projectile of paint which explodes upon impact.
 
      “Paint pellet gun” means any firearm, toy firearm or toy in the nature of a firearm which is powered by compressed gas and which fires paint pellets.
 
      “Replica firearm” means any device, object or facsimile made of plastic, wood, metal or any other material, that a person could reasonably perceive as an actual firearm but that is incapable of being fired or discharged, including, but not limited to, mobile phone cases, lighters, and cameras, except that the term shall not include any replica of an antique firearm, as defined in Section 8-20-010 of this Code. Each such replica firearm shall have as an integral part, permanently affixed, a blaze orange plug inserted in the barrel of such replica firearm. Such plug shall be recessed no more than six millimeters from the muzzle end of the barrel of such firearm.
 
   (c)   The manufacture, marketing, distribution, sale and possession of replica firearms are permitted if the devices are manufactured, marketed, distributed, sold or held solely for subsequent transportation in intrastate, interstate or foreign commerce. Such devices shall not be displayed to the general public or sold for other use in the city. The use or possession of a paint pellet or paint pellet gun is permitted if the use or possession is solely within premises licensed under Article III of Chapter 4-156 of this Code as a public place of amusement; or if the use or possession is solely for the purpose of transporting the paint pellet or paint pellet gun to or from those premises by the licensee or agent or employee of the licensee, or by a common carrier, for purposes of initial delivery, repair or disposal of the paint pellet or paint pellet gun.
 
   (d)   Any person who violates the provisions of this section, upon conviction thereof, shall be fined not less than $100.00 nor more than $750.00 for each offense. Any such violation may also be punishable as a misdemeanor by incarceration in a penal institution other than a penitentiary for up to six months under the procedures set forth in Section 1-2-1.1 of the Illinois Municipal Code as amended, and in the Illinois Code of Criminal Procedure, Illinois Revised Statutes, Chapter 38, Sections 100-1 et seq. (1985), as amended, in a separate proceeding. All actions seeking the imposition of fines only shall be filed as quasi-criminal actions subject to the provisions of the Illinois Code of Civil Procedure, Illinois Revised Statutes, Chapter 110, Section 1-101, et seq. (1985), as amended. Each purchase, use, sale, gift or transfer of any such replica firearm, paint pellet or paint pellet gun shall be deemed a separate and distinct offense, and each day a person unlawfully engages in the business of selling or exhibits for sale any such replica firearm, paint pellet or paint pellet gun shall be deemed a separate and distinct offense.
 
(Added Coun. J. 12-9-92, p. 25465; Amend Coun. J. 11-2-94, p. 58607; Amend Coun. J. 9-11-13, p. 59869, § 2; Amend Coun. J. 7-29-15, p. 2226, § 2; Amend Coun. J. 4-19-17, p. 48180, Art. V, § 5)

Sale to minors however is prohibited as stated here:

4-144-210  Sale or transfer to minors prohibited.
 
   It is unlawful for any dealer to sell, lend, rent, give or otherwise transfer an air rifle to any person under the age of 18 years where the dealer knows the person to be under 18 years of age, or where such dealer has failed to make reasonable inquiry relative to the age of such person and such person is under 18 years of age.
 
   It is unlawful for any person to sell, lend or otherwise transfer any air rifle to any person under 18 years of age.
 
(Added Coun. J. 12-9-92, p. 25465)

 This not only shows the lies of the Chicago government that says that air guns, airsoft guns and BB guns are illegal, which they are legal to own as according to those laws from their municipal code, but not to transfer or sell to anyone in city limits. You may not even lend it to someone under 18 as according to that ordinance. I would like the Chicago government to completely acquit any charges on anyone that has been prosecuted and imprisoned for possession of an air gun, airsoft or BB gun in the City of Chicago. This is completely unreasonable. Thank you and I hope this corrupt government of this City of Chicago will show some thought and action into freeing those who have been imprisoned for a toy and understand that airsoft guns are just toys. I appreciate anyone for signing this petition. Thank you very much.