Final answer:
The voting bloc that notably migrated to the Republican Party during the 1980s were labor unions. This shift was influenced by conservative economic policies promising growth and job creation under Ronald Reagan.
Step-by-step explanation:
The voting bloc that was largely notable in its migration to the Republican Party during the 1980s were labor unions. This shift is part of a broader historical trend known as realignment, wherein certain demographics shift their political affiliations. In the past, labor unions were strongly associated with the Democratic Party due to its support for workers' rights and progressive economic policies. However, during the 1980s, under the leadership of Ronald Reagan, many members of labor unions began to switch to the Republican Party, influenced by Reagan's conservative economic policies that promised growth and job creation which appealed to working-class voters. This was a significant part of the broader realignment that also saw southern White people and many northern members of the working class begin to vote for Republicans, as mentioned in the Sixth Party System.