Answer :

The main reason why the Reapportionment Act of 1929 was passed was because Congressional redistricting had gotten out of control to the point where people were losing votes. 
millermoldwarp

Correct answer:

The Reapportionment Act of 1929 was due to population changes. The population changes were due to the increase in immigration and the great change of population from rural to urban areas from 1910 to 1920. By the year 1929 no redistribution had taken place since 1911 and there was inequity in representation. For example some states had districts twice as large as others due to demographic change.