States with automatic 55 miles per hour

[surferdude]

Here is the law in PA....

§ 3362. Maximum speed limits.
(a) General rule.--Except when a special hazard exists that
requires lower speed for compliance with section 3361 (relating
to driving vehicle at safe speed), the limits specified in this
section or established under this subchapter shall be maximum
lawful speeds and no person shall drive a vehicle at a speed in
excess of the following maximum limits:
(1) 35 miles per hour in any urban district.
(1.1) 65 miles per hour for all vehicles on freeways
where the department has posted a 65-miles-per-hour speed
limit.
(1.2) 25 miles per hour in a residence district if the
highway:
(i) is not a numbered traffic route; and
(ii) is functionally classified by the department as
a local highway.
(2) 55 miles per hour in other locations.
(3) Any other maximum speed limit established under this
subchapter.
(b) Posting of speed limit.--
(1) No maximum speed limit established under subsection
(a)(1), (1.2) or (3) shall be effective unless posted on
fixed or variable official traffic-control devices erected in
accordance with regulations adopted by the department which
regulations shall require posting at the beginning and end of
each speed zone and at intervals not greater than one-half
mile.
(2) No maximum speed limit established under subsection
(a)(1.1) shall be effective unless posted on fixed or
variable official traffic-control devices erected after each
interchange on the portion of highway on which the speed
limit is in effect and wherever else the department shall
determine.
(c) Penalty.--
(1) Any person violating this section is guilty of a
summary offense and shall, upon conviction, be sentenced to
pay a fine of:
(i) $42.50 for violating a maximum speed limit of 65
miles per hour; or
(ii) $35 for violating any other maximum speed
limit.
(2) Any person exceeding the maximum speed limit by more
than five miles per hour shall pay an additional fine of $2
per mile for each mile in excess of five miles per hour over
the maximum speed limit.

[roadman65]

Here is the law in PA....

§ 3362. Maximum speed limits.
(a) General rule.--Except when a special hazard exists that
requires lower speed for compliance with section 3361 (relating
to driving vehicle at safe speed), the limits specified in this
section or established under this subchapter shall be maximum
lawful speeds and no person shall drive a vehicle at a speed in
excess of the following maximum limits:
(1) 35 miles per hour in any urban district.
(1.1) 65 miles per hour for all vehicles on freeways
where the department has posted a 65-miles-per-hour speed
limit.
(1.2) 25 miles per hour in a residence district if the
highway:
(i) is not a numbered traffic route; and
(ii) is functionally classified by the department as
a local highway.
(2) 55 miles per hour in other locations.
(3) Any other maximum speed limit established under this
subchapter.
(b) Posting of speed limit.--
(1) No maximum speed limit established under subsection
(a)(1), (1.2) or (3) shall be effective unless posted on
fixed or variable official traffic-control devices erected in
accordance with regulations adopted by the department which
regulations shall require posting at the beginning and end of
each speed zone and at intervals not greater than one-half
mile.
(2) No maximum speed limit established under subsection
(a)(1.1) shall be effective unless posted on fixed or
variable official traffic-control devices erected after each
interchange on the portion of highway on which the speed
limit is in effect and wherever else the department shall
determine.
(c) Penalty.--
(1) Any person violating this section is guilty of a
summary offense and shall, upon conviction, be sentenced to
pay a fine of:
(i) $42.50 for violating a maximum speed limit of 65
miles per hour; or
(ii) $35 for violating any other maximum speed
limit.
(2) Any person exceeding the maximum speed limit by more
than five miles per hour shall pay an additional fine of $2
per mile for each mile in excess of five miles per hour over
the maximum speed limit.

Back in 1988, the Welcome To PA sign on US 206 entering the state at Milford, did state "SPEED LIMIT IS 55 MPH UNLESS OTHERWISE POSTED."  I do not know if is still there or not, but it did have it and an END SPEED LIMIT xx where 55 mph always begun leaving lower limit areas.

[SidS1045]

Do they use the term "thickly settled" in the lawbook? How do they even define what is thickly settled and what isn't?

Massachusetts General Laws, Chapter 90, Section 1:

"'Thickly settled or business district', the territory contiguous to any way which is built up with structures devoted to business, or the territory contiguous to any way where the dwelling houses are situated at such distances as will average less than two hundred feet between them for a distance of a quarter of a mile or over."