As of the Twenty-First Edition of the Bluebook, "Citations to the federal code, whether official or unofficial, do not require a date."
Often a point of confusion for students. For print, you will choose the year of the volume that you are consulting. Where is the year? In order of preference: the spine; inside front cover, latest copyright year.
So what is the confusion? There are usually annotated unofficial codes and statute publications, ones that most people will use. However, there is often official codes (unannotated) for which the bluebook says you should cite in print (see Table 1). Thus, cite to the U.S.C. and not the U.S.C.A., or to the Mass. Gen. Laws and not the Mass. Gen. Laws Ann. A problem occurs in that the official codes are woefully slow to up-date in print. What do you do in that case?
The key phrase from the bluebook is use the official code "whenever possible." So if you need to cite to a statute section codified after a print version of the official code, you can refer to an unofficial annotated code. Further, citations can be made to an authenticated (Rule 18.2.1(a(i))) or official (Rule 18.2.1(a)(ii)) online version (though be careful, a site may look official, but not actually be so). Please note that no URL is required when citing to an authenticated source, according to Rule 18.2.1(a)(ii).
Massachusetts Administrative Procedure Act, Mass. Gen. Laws ch. 30A §§ 1-25 (2010).
7 U.S.C. § 281 (2006).
Generally, the order is Title of Act (if required), statutory compilation, some indication of location within (year).
For which federal code to cite to, see Rule 12.3 and "Cite the United States Code (U.S.C.), the official federal code, if available."
For state codes:
If citing multiple consecutive (sub)sections, use two section symbols, thus §§ (Rule 3.3(b)). If citing to separate sections, use two symbols, and list out the sections, e.g. §§ 3455(j), 3456(e). (see Rule 3.3(b))
When citing materials over multiple pages, always retain last two digits but drop repetitious digits, e.g. 1023-29, but 1123-1201 (Rule 3.2(a)).
Note that the 21st edition of the bluebook introduced Rule 3.3(d) regarding flush language.