The oldest areas on the east coast were settled before gas lines were a thing and electricity existed. So they use oil unless it’s a big city that paid to have gas lines installed.
This is why cities that grew a lot after gas was industrialized primarily have natural gas.
Remote areas will use oil, propane, or wood because they can be delivered by truck and heat pumps are a pretty new technology that hasn’t worked well in cold areas until recently.
The south has minimal heat requirements so they can get by with electric which is cheap to install but not efficient enough to provide primary heat in cold areas.
Also, southern homes generally have air conditioning so adding a reversing valve or set of heater coils is pretty easy.
One reason is bad laws. I would love to replace my natural gas boiler and steam radiators with an electric heat pump system. It would be more efficient, cheaper to run, be able use solar power, and keep my house more comfortable.
But state law requires that buildings meet a specific efficiency requirement, which my house does not meet because it is 170 years old. I understand why they have that requirement for new construction, but it is stupid to not have an exception for old buildings.
I was looking at what I'd need to get a heat pump installed yesterday, before the state website even started discussing the different types there were links to weatherization programs and efficiency requirements. My house is about 70 years old, even with insulation updates in the 00s it's a drafty bitch
Electric heating also works great basically everywhere else, too. Actually climate has very little to do with it in most cases and if there’s any non-manipulative reason(gas companies are really bad for this) it’s to do with what infrastructure makes the most sense.
In places like Québec we have electric heating because hydro makes electricity pretty cheap. Up north in Nunavut they will often have big tanks on the property and a truck will come by to refill them.
Do people in Southern California even need to heat their homes? Even in the Pacific Northwest close to the ocean (like Portland/Seattle) it doesn’t get below freezing much unless you’re at a higher elevation, so electric can still be adequate.
Age of the city and sufficient infrastructure. Once the building is built to use [oil or gas or whatever] it’s never refit to use something else. Something something quarterly profits.