Final answer:
There are several reasons why more districts have become safer for incumbent elections, including gerrymandering, the incumbency advantage, and the decline in partisan loyalties.
Step-by-step explanation:
There are several reasons why more districts have become safer for incumbent elections. One reason is gerrymandering, which is the drawing of district lines to guarantee a desired electoral outcome. When districts are gerrymandered to include a majority of Democratic or Republican Party members, candidates from those parties have an advantage.
Another reason is the incumbency advantage. Incumbents have name recognition, voting records, and the support of political action committees and interest groups. This advantage makes it difficult for competent challengers to defeat incumbents.
Lastly, the decline in partisan loyalties and the rise of voters identifying as Independent Party members have contributed to the electoral safety of incumbents. As a result, opposition candidates may be ineffective or lack quality, giving incumbents a greater advantage.