Comparison of 1976 Map and 1978 Map of Main Street
The 1978 map shows much less detail regarding the names of the stores on Main Street. It isn't clear to me whether this is due to store ownership changing, making it simpler to just leave the names off the map.
The copyright date is found to the left of the Disneyland title in banner at the bottom of the map.
Advertising the coming of Big Thunder Mountain Railroad. The emblem is located in the lower left corner.
Big Thunder Mountain Railroad
Although Big Thunder Mountain Railroad won't open until the next year, the 1978 map includes what the attraction will look like. This is likely because the previous attraction in this location, Mine Train Through Nature's Wonderland, had already closed and had been demolished.