Which countries have presidents mentioned the most in their State of the Union addresses? Which regions of the world get the most attention? And what trends can we discern over time?

First, a look at country mentions over time, broken down by region and plotted in two-decade increments (i.e., the 1800s covers 1800-1819).

I've highlighted five regions: Asia, Africa, Europe (including Russia), the Americas (North, South, and Central), and the Middle East (including North Africa's Muslim-majority countries, Turkey, Pakistan, and Afghanistan). I also didn't count presidential references to regions (e.g., "Europe" or the "Middle East").

The graph features two large spikes that are worth exploring. One appears between the 1820s and 1840s, when the young nation stepped up its efforts to establish diplomatic relations with European powers. The Americas also feature prominently during this period as the Spanish Empire disintegrates. Early American presidents, who viewed Simón Bolívar as a revolutionary in the mold of George Washington sought cordial relations with these nascent nations, which they frequently called "sister republics." (The Monroe Doctrine, which sought to check further European expansion in North and South America, was established in 1823.)

Around 1840, there's a sharp drop-off in country mentions as the national discourse turns toward deepening sectional tensions over slavery. In his first State of the Union address in 1861, Abraham Lincoln named only one other foreign power: Britain. But from there, other nations are only mentioned with increasing frequency as new embassies are established and distant powers like China and Japan open up.

But what about that big drop-off in the early 20th century? Foreign nations, it seems, are mentioned far less frequently after the State of the Union became a live speech in 1913. The change in format, along with post-World War I isolationism and the sharp turn to domestic policy following the 1929 Wall Street crash, appear to have fueled the initial decline. Other countries were only mentioned by name eight times in the 1930s—Franklin D. Roosevelt liked to paint in broad strokes—a 95-percent decline since the 1900s. Britain exemplifies this trend, as show by the graph below.

Britain is by far the most frequently mentioned country in State of the Union addresses, whether as Great Britain, England, the British Empire, or the British Commonwealth. Early presidents mentioned America's former colonial overlord in every State of the Union address between 1806 and 1886—a whopping 80 consecutive years.

Disputes over claims in the Treaty of Ghent, which ended the War of 1812, and ongoing border disputes with British Canada dominated 19th-century American diplomacy. After the Civil War, presidents most frequently discussed trade negotiations with both Britain itself and with its vast empire. After the two world wars, presidents mentioned Britain far less often, and it soon was superseded by variations of the common phrase "our European allies."

Although France was the first foreign power to formally recognize the United States, it was not the first country to be mentioned in a State of the Union address. That honor goes instead to Holland, now known as the Netherlands, whose loan of 3 million florins (a significant sum at the time) to the United States featured prominently in George Washington's December 1790 report to Congress.