I’ve been to every Canadian province and no territory. Although to be honest I spent only about 10 hours on PEI.
For US;
6 NE states. Then NY, NJ, PA, DE, MD, VA, NC, SC, GA, FL, AL, MS, WV, OH, MI, IL, MO, LA, TX, AZ, CO, CA, OR, WA, HI, AK. Seems like 30. Plus DC and PR.
I’ve been to 46 US states plus DC, Puerto Rico, & US Virgin Islands. My missing list is Alaska, Delaware, Maryland, & Rhode Island.
If I ignore the OP’s 24 hour rule, I can add Maryland with an asterisk, because when we were in DC we took a taxi through it for a few minutes on the way to & from the airport.
I’ve been to 6 Canadian provinces:
Alberta, British Columbia, Manitoba, Ontario, Quebec, & Saskatchewan.
You beat me my one: I never been to P.E.I. Like you, Alaska was the 50th.
Canada:
British Columbia
Alberta
New Brunswick
Yukon Territory
United States:
(live in) California
Never been to:
North Dakota
Wisconsin
Michigan
Vermont
Nebraska
Kansas
Missouri
Of the other 43 states:
Spent more than “drive through” time:
More than 2 nights, but less than 2 weeks:
Idaho
South Dakota
Wyoming
Minnesota
Maine
Massachusetts
Connecticut
Maryland
North Carolina
Florida
Utah
Washington
Texas
More than 2 weeks:
Pennsylvania
Virginia
New Mexico
Montana
Nevada
Ohio
Arizona
Colorado
Oregon
Alaska
Hawaii
The other 19 states I consider having “driven through”. More than just an airport stop, but not more than 2 nights as I passed through.
Never been to Canada.
I have been to 19 US states and Washington DC. Of those, I have lived in three states as an adult and five states overall.
49 states. (Have not yet made it to Alaska.)
9 Provinces. (Not yet been to Newfoundland & Labrador or to any territory.)
1 state in Mexico: Baja California.
I’ve never been a province or a state, alas. Not even a tiny little village. 
Provinces I’ve been to: BC, NS
States I’ve lived in: MI, IL, IA, CA, CT, VA, HI (7)
States/Territories I’ve spent at least one night in: OR, WA, OH, IN, PA, ME, MA, NE, CO, UT, FL, LA, MD, WI, MN, NY / GU, PR, VI (16/3)
States/Territories I’ve driven through: NV, NC, SC, GA, AL, MS, MO, KS, KY, WV, DE, NJ, RI, AZ, NH / DC (15/1)
States I’ve never visited: VT, TX, NM, OK, AR, AK, TN, ND, SD, MT, WY, ID (unless you want to count sitting in an airplane on the ground for an hour or so) (12)
Other countries I’ve visited: Japan, Hong Kong, Philippines, Thailand, S Korea, England, Scotland, Portugal, Spain, Norway, Italy, Greece, Bahrain, UAE, France, Gibraltar, Slovenia (not to mention Panama and Egypt – nice canals!)
Not too bad, considering that as of my 28th birthday I’d only been in nine states, all in the Midwest. “Join the Navy and see the world,” indeed.
That 24 hr rule, which I’m interpreting as 24 consecutive, really kills my totals. I’ve transited quite a fair number of states in a car or bus 
. But if I’m counting correctly just 19 states, D.C. and 3 provinces:
California (lived)
Washington state
District of Colombia (lived)
Illinois
Ohio
Michigan (lived)
Massachusetts (lived)
Pennsylvania
New York (lived)
Maryland
Virginia
South Carolina
Tennessee
Florida
Arizona
New Mexico
Utah
Colorado
Nevada
Hawai’i
British Colombia
Alberta
Ontario
Nevada and maybe Tennessee is a little touch and go - I think I’ve spent one full consecutive day in both, but it might have been just a little less than that. But I’ve certainly driven through Nevada often enough.
Yeah, I understand the point of the rule; it’s reasonable to make a distinction between visiting and passing through. But…
I’ve lived in DC for twenty-five years and worked in Maryland the whole time. We stayed one night in Baltimore, but I’m not sure I’ve ever spent 24 consecutive hours. So, I’ve never “been” to Maryland? Lots of people commute from New Jersey and Connecticut into NYC, but they’ve never “been” to New York?