Because of the way in which the Athenian Empire had arisen, it was a heterogeneous affair with an almost haphazard administration. First of all, some states retained a considerable degree of independence. They had their own fleets, kept their fortifications in good repair, and, in the case of a revolt, would prove difficult to defeat. For example, when Thasos revolted in 465, the Athenians’ siege of the Thasians lasted into the third year after an initial naval battle (Thuc. I 101; Diod. XI 70). The revolt of Samos in 440 nearly brought the empire to its knees (Thuc. I 115-117; Diod. XII 27-28). Athens always managed to keep control of its empire after such revolts, but they were frightening enough that allies with strong fleets and good fortifications retained considerable latitude in regulating their internal affairs. Mytilene maintained such a position down to the year 428 (Thuc. III 2sqq.); Chios and Methymna down until 411 when they finally revolted (Thuc. VII 57 and VIII 14 and 22).
Even states of far less importance than Mytilene and Chios could have such a position. The insignificant town of Potidaea, down to 432, still received its annual magistrates from its mother-city, Corinth (Thuc. I 56) - whether Athens allowed this anomaly for diplomatic reasons (relations with Corinth) or because Potidaea was too small for much concern, and as long as it paid the required tribute, the Athenians let it be. Potidaea’s position, even if strictly speaking unparalleled within the empire, is still compatible with the empire’s wide-ranging heterogeneity of administration; and it shows that other small cities, of which little is known, might still have possessed much freedom in regulating their own affairs.
Next, the Athenians tended to impose tighter control on individual states on a case-by-case basis rather than by uniform application of a rule. There was a garrison in some states (e. g., Erythrae - Fornara, Nr. 71), but not in all. Some states had Athenian governors (e. g., Miletus - Fornara, Nr. 92) or episkopoi, i. e., “inspectors” (e. g., Erythrae - Fornara, Nr. 71). The Athenians tended to impose or to restore democratic constitutions (e. g., in Eryrthrae - Fornara, Nr. 71; or on Samos - Diod. XII 28,4; cf. generally Diod. XIII 48,4). A few states (e. g., Histiaea - Thuc. I 114; Naxos and some cities on the Chersonese - Diod. XI 88,3) suffered perhaps the most hated penalty, namely the confiscation of land and the settlement of Athenians - a so-called cleruchy - on that land. But in no state were all of these things (garrison, governors, inspectors, democracy, cleruchy) to be found.
Despite this considerable heterogeneity some general conditions did apply. First, by the eve of the Peloponnesian War almost every state paid the tribute; and the Athenians had the authority to regulate the payment of the tribute (Fornara, Nr. 98) and to set its level (Fornara, Nr. 136). Second, the Athenians could and did ban the importation of goods from Megara into the empire (Aristoph. Ach., 517-522); later on the Athenians banned the entrance of the Megarians personally into the empire (Aristoph. Ach. 530-534; Thuc. I 67 and 139). Third, the Athenians could at least attempt to regulate currency throughout the empire (Fornara, Nr. 97); had they been successful in this, the empire would effectively have had a uniform currency.
Finally, as regards the assessment of the tribute, the Athenians by 442 BC had organized the tribute-paying members of the League (or Empire) into five districts (Carian, Ionian, Hellespontine, Thracian, and Island - see Meiggs 1972, Map I. i-vi). Regular tribute lists (Fornara, Nr. 85) recorded what each town was to pay annually, down to the obol (approximately half of one man’s daily wage at the time). Not for nothing did Thucydides call the Athenians “exact” in these matters (I 99).