Depends what country you are from. Here in Australia, our residential default is 50 km/h (31 mph) if unsigned.
30The speed limit in a California residential district is: 25(I just completed an online test so it is the correct answer)
Varies by state. Usually 25 to 35 MPH.
That depends on the laws relevant to the Country you live in, in the UK for example, most residential areas are limited to 30mph, however some are as low as 20mph.
25 miles per hour