Economic growth tends to proceed by surges and relapses, by over-investment booms and under-consumption crises. There can be unevenness both in the rate of expansion of the capacity to produce and in the degree of utilization of the productive capacity.
Unbalanced growth cannot be sustained long due to the emergence of bottlenecks. If, for example, the agricultural sector seriously lags behind the industrial sector, development may be interrupted through inflationary pressure or balance of payments disequilibria. Agriculture, on the other hand, unless it is totally export-oriented, cannot grow if the industrial sector is not able to develop sufficiently to create a steady increase in the demand for agricultural products. The heavy industry sector cannot grow irrespective of the wage-goods sector, for this may result in a general deficiency of demand.