This provides some links to the state statutes.
http://en.wikipedia.org/wiki/Stop_and_Identify_statutes
Looks like it might be Colorado. Also, CA used to require ID, but that appears to have been changed.
The other two states that even come close to demanding government issued identification are Montana and Indiana.
COLORADO
16-3-103. Stopping of suspect.
(1) A peace officer may stop any person who he reasonably suspects is committing, has committed, or is about to commit a crime and may require him to give his name and address,
identification if available, and an explanation of his actions. A peace officer shall not require any person who is stopped pursuant to this section to produce or divulge such person's social security number. The stopping shall not constitute an arrest.
MONTANA
HTTP://data.opi.mt.gov/bills/mca/46/5/46-5-401.htm
46-5-401. Investigative stop and frisk.
...
(2) A peace officer who has lawfully stopped a person or vehicle under this section may:
(a) request the person's name and present address and an explanation of the person's actions
and, if the person is the driver of a vehicle, demand the person's driver's license and the vehicle's registration and proof of insurance; ... [remainder not quoted]
History: En. 95-719 by Sec. 4, Ch. 513, L. 1973; amd. Sec. 8, Ch. 184, L. 1977; R.C.M. 1947, 95-719(1) thru (3); amd. Sec. 42, Ch. 800, L. 1991; amd. Sec. 1, Ch. 343, L. 2003.
INDIANA
HTTP://www.in.gov/legislative/ic/code/title34/ar28/ch5.HTML
Refusal to identify self
IC 34-28-5-3.5
Sec. 3.5. A person who knowingly or intentionally refuses to provide either the person's:
(1) name, address, and date of birth;
or
(2) driver's license, if in the person's possession; to a law enforcement officer who has stopped the person for an infraction or ordinance violation commits a Class C misdemeanor.
As added by P.L.1-1998, SEC.24
Note: All three require either the commission of an infraction or at least a suspicion of a crime.
Colorado says it may be DEMANDED, IF available
Montana says an offer may REQUEST unless one is driving and then it may be DEMANDED.
Indiana says one must provide one OR the other, but only with RAS.
My solution to any of those is to just leave my driving license in the car. In the last three years I've been requested only twice to produce identification (outside of L.E. encounters of which there have been exactly none), and that was to pick up items ordered through WallyWorld. They had no problem accepting my Passport Card which only identifies me as an American citizen without providing any address.