These specific occasions reflect attitudes about the broader ideas of multiculturalism and diversity.
Multiculturalism in one sense is simply the recognition of the cultural diversity that exists in nearly any given group of people. This common sense observation transcends political ideology.
Multiculturalism in another sense is the celebration of diversity, often accompanied by efforts to increase that diversity. This is where conservatives and liberals part ways.
The United States always has been a diverse nation. Even though the vast majority of settlers and immigrants came from Great Britain, significant and enduring differences marked those first generations of Americans. These differences included speech patterns, housing, food, marital and child rearing practices, and nuanced differences about the concept of liberty. You can read about it here. They did share, however, a broader culture unity rooted in language, religion, law, and national identity.
Over the decades, the United States has grown even more diverse. Millions of immigrants speaking different languages, worshiping different gods, and carrying cultural baggage very different from Great Britain and Europe have come to American for freedom and opportunity. Over several generations most of these immigrants have assimilated to varying degrees--most adopting English as their primary language and conforming to general American cultural norms--even while retaining important elements of their own important cultural practices. This state of affairs is captured by the by the historical metaphor of America as a "Melting Pot."
Our immigration policies helped preserve this state of affairs. Policies based quotas and caps for immigration on existing percentages of the population. In effect, this gave preference to immigrants who largely shared European cultural norms. This helps maintain something of a cultural continuity even in the face of technological change.
Most Americans in general, and Conservatives in particular, have embraced this vision of society as a unity that also preserves diversity. It conserves the core of American cultural norms; at the same time it defers to immigrants the freedom to maintain some of their own traditional cultural norms. Conserving our cultural norms is desirable because, first, they are ours, and second, they best maintain the conditions for human thriving. Conservatives recognize that some cultural practices are superior others.
Liberals have challenged this traditional approach to diversity. The Immigration and Naturalization Act of 1965 fundamentally changed our policies. The United States opened its doors to much larger numbers of immigrants from third world countries. Like most earlier immigrants, they, too, have come for freedom and economic opportunity. Unlike most earlier immigrants, however, their cultural norms differ in fundamental ways. Assimilation becomes more difficult. The incentive to assimilate grows weaker, too, when a continual stream of immigration reinforces the cultural practices of the native country. This is especially true of immigration from Central and South America. Moreover, the emergence of Telemundo and Univision as sources of entertainment and news for America's Hispanic population additionally acts as a disincentive for assimilation.
Sometimes assimilation is actually discouraged. Modern liberals have abandoned the earlier consensus on diversity by celebrating cultural diversity and encouraging its persistence. Liberals condemn even the most benign efforts to encourage greater assimilation--for example, English usage for communication--as racist. Some liberals seem to celebrate every culture but their own.
Finally, many liberals even abandon the pretense of immigration laws altogether. They welcome and encourage illegal immigration. When borders and laws do not matter, it is outsiders who determine our immigration policy--not us.
As Conservatives suspect, the results of such policies are not encouraging. Harvard political science professor Robert Putnam published a lengthy study of the relationship between diversity and social trust. Diversity not only erodes trust between ethic groups, it also erodes trust of a community's traditional social institutions.
The money quote:
"The effect of diversity is worse than had been imagined. And it’s not just that we don’t trust people who are not like us. In diverse communities, we don’t trust people who do look like us."
—Harvard professor Robert D. Putnam