Data on speakers of languages other than English are available from several sources:
U.S. Census Bureau (CB):
“Quick Facts,” on the front page of the CB website the percentage of a state, city or county’s residents that speak a language other than English at home and those that are foreign born. These percentages can differ widely, even within a single county.
CB offers data on speakers of languages other than English and the foreign born. These numbers are available from the Census Bureau’s American Community Survey in yearly and 5-year estimates. The 5-year estimates are considered more accurate and also cover smaller geographies (with under about 300,000 inhabitants, including areas as small as a zip code or census tract) than the 1-year estimates. Click here to go to the American Community Survey. Once there, paste in the numbers of tables you’re looking for and choose geographies you’re interested in. The most informative tables for our purposes are Table B16001 (Language Spoken at Home by Ability to Speak English) and C05006 (Place of Birth for the Foreign-Born).
The newest CB tables released in 2015 include rarely-published detailed tables that show every language spoken in the U.S., states plus the District of Columbia and Puerto Rico, counties with over 100,000 with over 25,000 speakers of languages other than English and Spanish, and “core-based statistical areas.” These tables report on may more languages than the 39 listed in B16001.
CB publishes reports and releases on language topics (for example, here is a news item on the increasing number of foreign-born young adults who speak another language at home; and here's a report on “Language Use in the United States: 2011”). For more reports, check the CB’s Publications page under “Language Use.”
Pros of using CB Data: Comparing the percentage of people who speak an LOTE across geographies is interesting and informative, particularly in a multicultural area such as Los Angeles; so is comparing languages listed in B16001 from most to least spoken over time (to do that, remove the categories “speak English well” and “… less than well” by sorting this column in alphabetical order, and then sort by number in descending order).
Cons: The CB’s site could be more user-friendly than it is. Moreover, B16001 reports on only 39 languages and language groups. Some “groups” are not nearly differentiated enough; e.g., all African Languages are in a single group. As the number of African Language speakers grows, this category is increasingly hard to justify. Some small geographies are not captured by core-based statistical areas (e.g., Alhambra’s population of 79,422 includes a majority of residents who speak Chinese at home).
MLA Language Map. This user-friendly and attractive site offers census-based data on languages spoken in nationally and by state, county, and city from 2013’s American Community Survey. Data can be generated in the form of maps, tables, and graphs. The Language Map can be found here.
State departments of education (look up by state). Some department websites provide data on languages spoken by K-12 public school pupils, but type and availability vary by state. Each state presents data in its own way, and some do not seem to offer any data on line.
Other Possible Data Sources
Educational institutions often survey incoming students on their backgrounds; for example, here is a page from a report on UCLA’s 2013 entering class, which shows that 60% of this class speaks a language other than English, either as a native language (40%) or a heritage language (25%).
Language instructors can survey their own heritage learners or other members of the speech community. For some questionnaires that you can use or adapt, see NHLRC’s Research and Proficiency Assessments Tools.