The Ford Mustang, an American icon, has been in continuous production for over 50 years. The original 1965 Mustang was unveiled on April 17, 1964 at the New York World’s Fair. Since then, more than 9 million Mustangs have been produced.

The Mustang, now in its sixth generation, has went through many changes in design and performance as well as price. 24/7 Wall St. compared retail prices of the base model Mustang in each production year. The original base model cost $2,321 in 1965, or $17,447 in 2015 dollars. Since then, the price has increased to $24,645 for a 2017 Mustang, the most expensive base model in history. The base model Mustang was the cheapest in 1978, costing only $13,890.

Including the “1964 ½” models, as well as the infamous Shelby, 681,551 Mustangs were produced in 1965, more than in any other year. The number produced in 1965 was three times higher than the average annual production in the following 50 years.

Click here to see what a Mustang looked like the year you were born.

The standard Mustang engine has also changed considerably over the years. The first Mustang came standard with a 170 cubic inch, 6-cylinder engine producing 101 horsepower. As with many muscle cars in the 1970s, the oil crisis caused base model engines to shrink. In the Mustang’s case, a 4-cylinder engine with only 88 horsepower was standard for over a decade. Even the largest engine available in 1974 — directly after the 1973 oil embargo — was barely larger than the standard engine in the original Mustang and produced only 105 horsepower.

Mustang engines since 1990 have steadily increased in size, likely because of the resurgence of the muscle car culture. Since demand for early generations of muscle cars has increased from older Americans desiring to purchase the cars of their youth, many car manufacturers have revived models from the past or redesigned current models in a classic style. For the Mustang, this came in the form of the return of the Shelby, which alluded to the first generation with body styling, and a massive increase in engine size.

To compare the cost of a Mustang through the years, 24/7 Wall St. compared base model retail prices from 1964 ½ through 2015 as documented by Peter C. Sessler in the Mustang Red Book. The publication is not affiliated with the Ford Motor Company. We used the Red Book on the recommendation of Ford representatives, however. Inflation adjusted prices are in 2015 dollars. Production data and engine sizes are also from the Mustang Red Book.