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.

**(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.