765 ILCS 1005/1
No estate in joint tenancy in any lands, tenements or hereditaments, or in any parts thereof or interest therein, shall be held or claimed under any grant, legacy or conveyance whatsoever heretofore or hereafter made, other than to executors and trustees, unless the premises therein mentioned shall expressly be thereby declared to pass not in tenancy in common but in joint tenancy; and every such estate other than to executors and trustees (unless otherwise expressly declared as aforesaid, or unless, as to a devise or conveyance of homestead property, expressly declared to pass to a husband and wife as tenants by the entirety in the manner provided by Section 1c), shall be deemed to be in tenancy in common and all conveyances heretofore made, or which hereafter may be made, wherein the premises therein mentioned were or shall be expressly declared to pass not in tenancy in common but in joint tenancy, are hereby declared to have created an estate in joint tenancy with the accompanying right of survivorship the same as it existed prior to the passage of "An Act to amend Section 1 of an Act entitled: 'An Act to revise the law in relation to joint rights and obligations,' approved February 25, 1874, in force July 1, 1874," approved June 26, 1917.
765 ILCS 1005/1