Via a tweet from Dan Drezner, here’s a chart showing every US military action abroad since 1798:
There are reasons to take this with a grain of salt. The CRS report it’s based on includes purely humanitarian missions (“2014: Southern Philippines Humanitarian Assistance for Typhoon Bopha”) and it also seems to count separate actions in a single conflict as distinct uses of force (1994 includes five separate entries for Bosnia).
That said, we sure do send our military abroad a lot, don’t we? If I’ve counted correctly the longest span without a military action overseas was 1934-40, when I guess we were too busy with the Depression to flex our muscles.