Maybe I'm misreading this, but it looks to me like Oregon requires any
general aviation pilot who flies into or through Oregon must then
register with the Oregon Department of Aviation within 60 days. Unless
they have some other meaning for "operating"? Likewise, in all the
material I've ever read on acquiring a pilot certificate, this is the
first time I've read that there are additional state requirements! How
many states have laws like this? Here's the text of the law and links to
the entire context for anyone who can help me understand what this really
means:

"837.020 Registration of pilots; renewal. (1) In the interest of public
safety and the safety of those people traveling by air or receiving
aviation instruction, every pilot operating within this state shall
register with the Oregon Department of Aviation within 60 days of
issuance of any appropriate effective federal certificate, permit, rating
or license relating to competency as a pilot except that student pilots
shall register prior to their first solo flight. A nonresident pilot of a
scheduled or nonscheduled airline, certificated by the appropriate
federal agency, is not required to register under the provisions of this
section unless the nonresident pilot engages in the piloting of aircraft
other than such certificated operation. Nonresidents operating within
this state, other than in a commercial operation, shall register with the
department within 60 days of the date of arrival within the state. Pilots
operating commercially shall register prior to any commercial operation.

(2) Every registered pilot shall renew the first registration on
the anniversary of the pilot’s birthdate. After the first renewal, each
pilot shall renew registration on the anniversary of the pilot’s
birthdate in the first year of each two-year period thereafter in which
the pilot is active as a pilot.

(3) Every registered pilot shall notify the department in writing
within 30 days of a change of address or name. The notification shall
contain the old and new residence address or name and the pilot
registration number. [Formerly 493.040; 1991 c.186 §1]

837.025 Requirements for pilot registration; fees; certificates.
(1) Possession of the appropriate effective federal certificate, permit,
rating or license relating to competency of the pilot and payment of a
fee of $8 for initial registration and $16 for each renewal of
registration shall be the requisite for registration of the pilot under
ORS 837.020. A filing of a written statement containing the information
reasonably required by the Oregon Department of Aviation is sufficient to
effect a registration. No originals or copies of federal certificates,
permits, ratings or licenses shall be required of the applicant.
Duplicate certificates of pilot registration may be obtained upon proof
of loss or destruction of the original by application therefor to the
department and the payment of $5 for each additional certificate.

(2) The department may issue certificates of registration and may
prescribe requirements for possession and exhibition of such
certificates.

(3) Information submitted in any application for registration is a
public record and is open to public inspection during normal office
hours. [Formerly 493.050; 1991 c.206 §1; 1997 c.585 §3]"

http://landru.leg.state.or.us/ors/837.html
http://www.oregon.gov/Aviation/registration.shtml