Requirement	Urban Employment Area
Categories	Metropolitan Employment Area: The DID population of the core is at least 50,000 Micropolitan Employment Area: The DID population of the core is at least 10,000 and less than 50,000
Qualification of Areas	City of at least 10,000 DID population
Qualification of central municipalities (Cores)	Municipalities that satisfy either of the following two requirements are included in the core. (The core may include more than one municipality.) (a) The DID population is at least 10,000 and the municipality is not an outlying area of another core. (b) The requirements for an outlying area are satisfied and the following two requirements are also satisfied. (i) The employees-to-residents ratio is at least unity. (ii) The DID population is at least 100,000 or one third of the core. For a pair of municipalities each of which satisfies the requirement for being in a core and also satisfies the commuting-ratio requirement for being an outlying area of the other municipality, the one with the lowest commuting ratio is in the core and the other is its outlying area.
Qualification of outlying municipalities	(a) A municipality is a first-order outlying area of a core if at least 10% of its employed residents work in the core. (b) A municipality is a second-order outlying area of a core if at least 10% of its employed residents work in an outlying municipality and the commuting ratio to the municipality is the highest among all target municipalities. Higher-order (i.e., third-order, fourth-order, etc.) outlying municipalities are defined analogously. (c) If a municipality satisfies requirement (a) for more than one core, it is included in the outlying area of the core with which it has the strongest commuting ties. (d) If a municipality satisfies the requirement for an outlying area of a core as well as for another outlying municipality, it is an outlying area of the one with which it has the highest commuting ratio.

Conditions for a core:
(a) The first round core candidates are municipalities with DID populations of at least 10,000.
(b) A municipality that is an outlying area of another central city is excluded from being a core.
(c) For a pair of municipalities that each satisfy the requirement for being in a core and also satisfy the commuting-ratio requirement for being an outlying area of the other municipality, the one with the lowest commuting ratio is in the core and the other is its outlying area.
(d) An outlying municipality is included in the core if the following two requirements are satisfied. A 'major' city (known as a Seirei Shitei Toshi) for which data on its wards are available is included in the core if at least one of its wards satisfies the following requirements.
(i) The employees-to-residents ratio (i.e., the ratio of the number of employees to the number of residents) is at least unity.
(ii) The DID population is at least 100,000 or one third of the core.

Conditions for an outlying area
(a) A municipality is an outlying area of a core if at least 10% of its employed residents work in the core.
(b) If a municipality satisfies condition (a) for more than one cores, then it is included in the outlying area of the one with the strongest commuting tie.
(c) A second-order outlying municipality that is an outlying area of another outlying municipality is included in a UEA. Higher-order outlying municipalities (i.e., third-order, fourth-order, etc.) are also included in UEAs. The criterion for a second-order municipality is that, of all the target municipalities, its commuting ratio to a first order outlying municipality is the highest and satisfies the 10% criterion. Higher-order outlying municipalities are defined analogously.
(d) If a municipality simultaneously satisfies the requirement for being an outlying area of a core and the requirement for being another outlying municipality, it is classified as an outlying area of the one with which it has the highest commuting ratio. That is, if 16% of the employed residents in city A work in core B and 17% of them work in city C, which is an outlying municipality of core B, then city A is an outlying area of city C.

Revisions

Municipality codes correspond to those used in each census year and may therefore differ across years due to municipal mergers and other administrative changes.
The 2000-standard UEA was added. (November 11, 2002)
An error in the 1990-standard UEA was corrected: Hamura Town (Tokyo) had been listed both as a second-order outlying area and as a core municipality of the Tokyo UEA. (November 11, 2002)
A bug in the program used to define the 1990-standard UEAs was fixed. (November 19, 2002)
A problem in the 2000-standard MEA was corrected: the number of out-commuters from Tachikawa Town (code 6421, Yamagata Prefecture) to both Tsuruoka and Sakata happened to be exactly equal (443 each), causing the town to be listed in both UEAs. Including commuters aged 15 and over who are enrolled in school, the flow to Sakata was larger, so Tachikawa Town was reclassified as a first-order outlying area of Sakata.
Tomika Town (code 21502) had been listed as an outlying area of Seki (code 21205), but its commuting ratio to Minokamo (code 21211) was higher. It was therefore reclassified as a third-order outlying area of Minokamo (which is a second-order outlying area of Kani, itself a first-order outlying area of Nagoya). This applies to the 1990-, 1995-, and 2000-standard UEAs; no correction was required for the 1980 standard. This was pointed out by Mr. Kota Sakado (Graduate School of Media and Governance, Keio University). (September 2007)
In the 1990-standard UEA, Ritto Town had been registered as a McEA core despite being classified as a third-order outlying area of Kyoto. It was removed from the McEA core list. (September 2007)
The 2005-standard UEA was added. (August 3, 2009)
The 2010-standard UEA was added. (October 22, 2015)
The 2010-standard UEA data were revised. (December 3, 2015)
The 2020-standard UEA was added. (April 2026)
There was a typographical error in the manual (CSIS DP 188): the code for Futaba Town should be "07546", not "05746". We thank Mr. Kobayashi of Keikaku Kenkyusho for pointing this out. (April 2026)

(1) The First Iteration
(a) Choose municipalities with DID populations of at least 10,000 as candidates for central cities.
(b) Exclude as potential central cities defined by (a) those municipalities that are outlying areas of other potential central cities.
(c) Determine the outlying municipalities for the potential central cities by using the following procedure.
(i) Select municipalities for which the percentage of employed residents who work in a central municipality is at least 10%; and for each of them, determine the central municipality that has the highest commuting ratio. This identifies potential first-order outlying municipalities.
(ii) Determine potential second-order outlying municipalities by choosing municipalities that satisfy the commuting-ratio criterion.
(iii) Determine potential second-order outlying municipalities.
(iv) Determine potential third-order outlying municipalities.
(v) Check for fourth-order outlying municipalities. (Currently, there are none.)
(vi) If a municipality is simultaneously a first-order, second-order, and/or third-order outlying area, identify the target municipality with the highest commuting ratio.
(vii) List the outlying municipalities for each central city.

(2) The Second Iteration
(a) Of the potential outlying municipalities identified in the first iteration, those that satisfy the following two requirements are included in the cores of the UEAs to which they belong. If a candidate is a 'major' city, it is included in the core if at least one of its wards satisfies the following requirements.
(i) The employees-to-residents ratio is at least unity.
(ii) The DID population is at least 100,000 or at least one third of that of the central municipality.
(b) Potential first-order outlying municipalities are those in which at least 10% of employed residents work in the central municipality. For each of these, choose the central municipality that has the highest commuting ratio. The procedures applied in the first iteration are applied to determine higher-order outlying municipalities.

(3) The Third and Further Iterations
The procedures used in the second iteration are used for subsequent iterations. Step (a)(ii) in the second iteration for adding an outlying municipality to the core remains the same. In particular, the central municipality is the one identified in the first iteration and does not include those added in the second iteration.