From the Disney Channel, in 1988:
It’s hard to believe that 1988 was the last time the Disney company publicly celebrated Mickey’s birthday – in this case, his 60th. Back in the 1980s and early 1990s, Disney park celebrations were often centered on specific anniversaries or events. In 1981 it was Walt Disney World’s “Tencennial”. In 1984 it was Donald Duck’s 50th birthday. Walt Disney World celebrated its 15th birthday in 1986, and 1987 marked the bicentennial of the United States Constitution. This approach gave the celebrations the feel of a real “event,” and the result was that they were far more distinctive than today’s “Celebrate Dreams”, “Celebrate Wishes”, and “Celebrate Celebrations” approach.
Despite this clip’s justification for the “Happy Birthday from Across the USA” theme of Mickey’s birthday parade, the actual reason for the theme was that it allowed for the re-purposing of 1987’s “All-American Parade.” Not that I can blame the company; this was a massive and lengthy parade with many elaborate floats and set pieces and it was re-used several times in the late 1980s.
Of course, the other in-park recognition of Mickey’s 60th was the all-new Mickey’s Birthdayland, a “temporary” attraction that would eventually turn into today’s Mickey’s Toontown Fair.