In numismatic lingo, the terms “year” and “date” may seem interchangeable. However, the phrases actually have two totally different meanings. When collectors refer to a rare “date” they are most likely alluding to the combination of year and mintmark. In the Morgan Dollar series, for instance, the date 1889-CC is an extremely rare issue that carries a tremendous premium in all grades. As a year, however, 1889 is not rare. One can buy an 1889 Philadelphia issue (i.e. a coin without a mintmark) for less than $50 in average grades.
Some years are extremely scarce regardless of mintmark. Using the Morgan Dollar as an example again, 1895 is a rare year for all three mints. 1895 Philadelphia issues are five-figure coins in all grades, the 1895-O is a semi-key date, and the 1895-S is valuable in any level of condition. The same phenomenon can be seen in other series. For Walking Liberty Half Dollars, the year 1921 is extremely challenging regardless of mintmark. The 1921 Philadelphia, Denver and San Francisco issues are all quite valuable.
For collectors, assembling a year set instead of a complete date set can mean substantial savings. Many United States coinage series have one or more wildly rare issues that are well beyond the average collector’s budget. An excellent example is the 1854-1889 $3 Gold “Princess” series. One date, the 1870-S, has exactly one piece known. The unique coin is currently impounded in a museum but, if offered for sale, would fetch a seven-figure amount. With this coin unavailable to collectors are any price, assembling a year set instead of a date set is a much more affordable (and plausible) option. In a year set, a collector could buy a relatively inexpensive 1870 Philadelphia piece for $2000-$3000.
Returning to the Morgan Dollar series again, a year set offers tremendous advantages over a date set. There are over a dozen key and semi-key Morgans, including the 1879-CC, 1889-CC, 1892-S, 1893-S, 1893-CC, 1894, 1895, 1895-O, 1901 and others. This pushes the cost of a complete set in average circulated grades to $50,000 to $75,000 while an Uncirculated set would run well in excess of $100,000. Meanwhile, a date set in similar grades can be had for under $5,000 in circulated grades and under $10,000 in Mint State. In essence, pursuing a year instead of instead of a complete date set (i.e. every year and mintmark combination) will save a collector more than 90%.