Abstract
Regional inequalities are currently a challenge for the majority of countries, in particular large ones, certain of which are federations. The federal state system is more complex than the unitary system. This results in specific problems. One of them is the issue of differing level of economic development of individual territorial units, whereby the problem of income redistribution emerges. The difference between income and expenses results in the formation of fiscal gaps, both horizontal and vertical ones. The aim of the paper is to present the measures applied for measuring the horizontal fiscal imbalance. It is also the starting point for conducting measurements of those imbalances in the USA based on the presented measures. The paper presents the measures applied in the literature for the purposes of measuring horizontal fiscal imbalance. In addition, the measurement of those imbalances in the USA are presented.