DialWick · Number Directory
Where a phone number is really from, and why.
Area codes, ZIP codes, counties, and international dialing formats -- sourced from NANPA, USPS/Census data, and current carrier records, with the split-and-overlay history and local context a one-line answer leaves out.
Area Codes
State and province lists, individual lookups, and how the numbering plan actually works.
01 Every Michigan Area Code, and the Split Tree Behind Detroit's Newest Michigan has 13 area codes today, seven descended from Detroit's original 313. Here's the full list, plus the split-and-overlay chain behind each one, including the newest, 679. 02 Every North Carolina Area Code, and the One About to Get Company North Carolina has 10 area codes today, all descended from the single code assigned to the whole state in 1947, and regulators are now weighing an overlay for the one region still running on just one. 03 Every New Jersey Area Code, and the Day Three of Them Launched at Once New Jersey has 10 area codes today, all descended from a single statewide code assigned in 1947, including three overlays the state's utility board activated on the exact same day in 2001.
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City ZIP code lists and county breakdowns, sourced from USPS/Census data.
01 Kansas City ZIP Codes: Two Cities, Two States, Two Separate Lists Kansas City is really two cities in two states. Every ZIP for Kansas City, Missouri (71, three counties) and Kansas City, Kansas (15, one county). 02 Cincinnati ZIP Codes: All 71, and Two That Aren't in Hamilton County Cincinnati's 71 ZIP codes almost all sit in Hamilton County, except one that's a 20,000-person Clermont County suburb, and one that's an 18-box mail drop with no residents at all. 03 Houston ZIP Codes: The Full List, and the Independent City Filed Under Houston's Name Houston has 178 ZIP codes in two postal blocks, and one of them, 77005, belongs to a city that has never joined Houston, while its equally independent neighbor Bellaire got a ZIP name of its own instead.
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Which county a major US city actually sits in.
01 What County Is San Antonio In? 82 of San Antonio's 83 ZIP codes sit in Bexar County, Texas; the other reaches into Comal County next door. Bexar itself once covered nearly all of West Texas, before 128 of today's counties were carved out of it. 02 What County Is Houston In? Houston's 178 ZIP codes sit entirely inside Harris County; only small annexed strips of the city itself dip into Fort Bend and Montgomery. Harris is closing the population gap on Chicago's Cook County. 03 What County Is Chicago In? All 84 of Chicago's ZIP codes sit inside Cook County; only the city's O'Hare strip dips into DuPage. Cook is the second-most-populous US county, and it's growing again, not losing ground to Harris County.
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Current dialing formats for calling abroad from the US.
+81 Japan's Country Code Is +81, and Its New 060 Prefix Just Got Delayed Dial 011, then 81, then drop the leading 0. Japan's area codes shrink as cities grow, and a fourth mobile prefix, 060, was due this year before carriers postponed the rollout. +33 France's Country Code Is +33, and a 2005 Rule Still Shapes Its Freebox Numbers Dial 011, then 33, then drop the leading 0. France's five regional zones trace to a 1996 overnight switch, and its 09 prefix exists because of a 2005 fix for VoIP boxes like Freebox. +44 The UK's Country Code Is +44, and Most Britons Get Their Own Area Code Wrong Dial 011, then 44, then drop the leading 0. London's real area code is 020, not "0207" or "0208"; a study found only 13% of people could name it correctly.
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