Chronicling America API in Matlab

by Anastasia Ramig

LOC Chronicling America API Documentation: https://chroniclingamerica.loc.gov/about/api/

These recipe examples were tested on December 6, 2022 in MATLAB R2022b.

Attribution: We thank Professor Jessica Kincaid (UA Libraries, Hoole Special Collections) for the use-cases. All data was collected from the Library of Congress, Chronicling America: Historic American Newspapers site, using the API.

Note that the data from the Alabama state intelligencer, The age-herald, and the Birmingham age-herald were contributed to Chronicling America by The University of Alabama Libraries: https://chroniclingamerica.loc.gov/awardees/au/

1. Basic API Request

The Chronicling America API identifies newspapers and other records using LCCNs. We can query the API once we have the LCCN for the newspaper and even ask for particular issues and editions. For example, the following link lists newspapers published in the state of Alabama, from which the LCCN can be obtained: https://chroniclingamerica.loc.gov/newspapers/?state=Alabama

Here is an example with the Alabama State Intelligencer:

%% set up the API parameters and pull json data for the given LCCN
api_url = "https://chroniclingamerica.loc.gov/lccn/";
lccn = "sn84023600";
q = webread(api_url + lccn + ".json")

Output:

q = struct with fields:
 place_of_publication: 'Tuskaloosa [sic], Ala.'
                 lccn: 'sn84023600'
           start_year: '183?'
                place: {'Alabama--Tuscaloosa--Tuscaloosa'}
                 name: 'Alabama State intelligencer. [volume]'
            publisher: 'T.M. Bradford'
                  url: 'https://chroniclingamerica.loc.gov/lccn/sn84023600.json'
             end_year: '18??'
               issues: []
              subject: []

%% extract the name from the search
q.name

Output:

ans = 'Alabama State intelligencer. [volume]'

%% extract the publisher from the search
q.publisher

Output:

ans = 'T.M. Bradford'

Moving on to another publication, we can get the 182nd page (seq-182) of the Evening Star newspaper published on November 19, 1961.

%% set up the API parameters and pull json data for the given LCCN
lccn2 = "sn83045462/1961-11-19/ed-1/seq-182";
q2 = webread(api_url + lccn2 + ".json");

%% obtain the url for the pdf of the page
q_url = q2.pdf

Output:

q_url = 'https://chroniclingamerica.loc.gov/lccn/sn83045462/1961-11-19/ed-1/seq-182.pdf'

%% view the PDF in web browser
web(q_url)

2. Frequency of “University of Alabama” mentions

The URL below limits to searching newspapers in the state of Alabama and provides 500 results (as a demo) of “University of Alabama” mentions. Note that phrases can be searched by putting them inside parentheses for the query.

%% set up the API parameters and pull json data
api_url = "https://chroniclingamerica.loc.gov/search/pages/results/?state=Alabama&proxtext=(University%20of%20Alabama)&rows=500&format=json";
options = weboptions('Timeout', 30);
alabamaInfo = webread(api_url, options);

%% find the size of the data structure
size(struct2table(alabamaInfo.items))

Output:

ans = 1x2
500    28

%% extract the years from the dates given
dates = {alabamaInfo.items.date};
datesList = {ones(length(alabamaInfo.items), 1)};
for i = 1:length(dates)
   datesList{i} = str2double(dates{i}(1:4));
end
%% plot a histogram of the mentions according to decade
x = cell2mat(datesList);
edges = [1890 1900 1910 1920 1930];
xticks = ([1890, 1900, 1910, 1920]);
histogram(x, edges)
title("Mentions of University of Alabama by Decade");
xlabel("Decade");
ylabel("Mentions");

Output:

3. Industrialization keywords frequency in the Birmingham Age-Herald

We will try to obtain the frequency of “Iron” on the front pages of the Birmingham Age- herald newspapers from the year 1903 to 1949 (limited to first 500 rows for testing here).

%% set up the API parameters and pull json data for the given parameters
api_url = "https://chroniclingamerica.loc.gov/search/pages/results/?state=Alabama&lccn=sn85038485&dateFilterType=yearRange&date1=1903&date2=1949&sequence=1&andtext=Iron&rows=500&searchType=advanced&format=json";
ind = webread(api_url, options);

%% create a dataset of dates and format as datetimes
dates2 = {ind.items.date};
x2 = datetime(dates2, 'InputFormat', "yyyyMMdd");

%% plot a histogram of mentions of iron by year
histogram(x2.Year, 'BinMethod', 'integers')
title("Iron Frequency in the Birmingham Age Herald");
xlabel("Year");
ylabel("Mentions");