The first stop in Alto Maipo is Macul, at the southern city limits of Santiago, hidden from view behind a seemingly endless, curving wall. Beyond the gates of this wall is a private parque with ancient trees, ornate bridges over streams, banks of flowers. It's part of the original land grant Juan Jufré received from Pedro de Valdivia, his brother-in-arms who he'd helped in the conquest of Santiago. Jufré planted the first vines here in the middle of the 16th century, and some of the stalwart país was still alive when Matías Cousiño bought the 2,500-acre Hacienda Macul in the mid-19th century. His was one of the mining fortunes earned in the north of Chile; his son, Luis, got busy spending that fortune on wine.
  In 1860, Luis brought cabernet sauvignon vines from the Médoc to replant the old vineyards (the Cousiños believe these vines came from Cos d'Estournel). Those first cabernet vines in the Alto Maipo spread south, forming the string of vineyards which a 19th century traveler might have imagined as a mirror image of the Haut-Médoc, the Bordeaux district north of the city from Margaux to St-Julien, Pauillac and St-Estèphe. The reality for the vines, however, is significantly different.
  While their original home had been a wash of gravel along the Gironde estuary, they now set their roots in alluvial soils. And if the often long, cool growing season of Bordeaux is moderated by the Atlantic, here in Maipo, the tempering factor is the Andes. What makes the Alto Maipo cabernet distinct is not only the rocky soils in which it grows, but the significant shift from the high day-time temperatures into the night, when cold air washes down the hills. In Puente Alto, where this diurnal shift can be the greatest, it may reach 100° F at 2:30 in the afternoon, and drop to 55° by 7:30 the next morning. Those cold Andean nights slow the ripening process and maintain acidity in the grapes.

One hundred fifty years later, cabernet sauvignon has taken on its own distinct profile in Alto Maipo, especially when farmed with low-yielding care. It produces wines with an elegant line of currant flavors over a mineral-tinged structure, such as the 2001s from Almaviva in Puente Alto or Terrunyo from Pirque Viejo. But wines of such underlying strength and complexity are a relatively recent phenomenon. In the past fifteen years, there's been tremendous viticultural change in Chile, and along with it, a change in philosophy.
  For decades, Chilean wines have been promoted as brands. Many of Chile's most significant players have a base in the Alto Maipo, but make most of their wine from Central Valley grapes. The contemporary emphasis on viticulture has begun to replace the preeminence of winemaking, and the focus of the wines has begun to shift from brand to land. Now, as the international market has tightened and Chileans work to distinguish their best wines, defining that land has become a priority. That means separating it from other land of lesser or different distinction.
  For the last three years, Isabel Guilisasti of Concha y Toro has led the discussion of one such distinction: the Alto Maipo. She has worked toward an agreement between all the players in the four zones to create a new organization, one that combines the zones under the Alto Maipo name. It creates a structure by which to promote the wines - and a lens through which buyers can view them. Though this may seem a small step from an outsider's point of view, it is, in fact, the first time such a politically charged change would be made in Chilean viticulture.
  Back in 1994, the Chilean government's viticultural department (a division of SAG, the agriculture and livestock service) set up a commission to divide the country into viticultural regions. According to Antonio Aluanlli, who heads the department, the divisions were based on political boundaries rather than terroir. The commission, including members of the government, the wine industry and technicians, discussed the possibility of being more specific about climate and topography, but they decided to begin with the political boundaries and allow the future creation of new defined areas.
  It took the commission a year to make their decision. Now it's taken the producers in the Alto Maipo three years to take the first step toward a much more difficult decision. They've parsed the history, the climate and the soil. "Now the problem is to create a geographical limit," Guilisasti explains. "We're working with a topographer to establish whether [the limit of the zone] is 1,300 or 1,475 feet altitude, in reference to the Andes (not the Coastal mountains)." Once they draw the line, it may well change land values and wine prices on either side of the border. Consider the value of a Napa Valley name on a label, and how that name has affected land prices to get a sense of the potential impact of this new organization. Such a step is critical, however, in helping to communicate the character of Chile's prime cabernet terroir through the wine itself.

It would be wrong to assume that the conditions in all four Alto Maipo zones are similar. Their soils vary, as does their share of Andean influence due to the altitude of the vines; proximity to the Maipo River is a factor as well. These differences remain the biggest hurdle in creating the new appellation. It is relatively easy to argue that although the three estates around the old Hacienda Macul in Santiago have a more extreme condition than the vineyards in Puente Alto and Pirque, they all share important climate factors. The three zones are above 2,000 feet, where the cold nights extend the ripening to more than five months between flowering and harvest. Heading south, lower mountains separate Pirque from Alto Jahuel and the higher districts of Buin. Here, another historic 19th century cabernet vineyard surrounds the Casa Real at Viña Santa Rita. The vines grow at 1,492 feet, and typically have a four-month ripening cycle. On the other hand, Santa Rita has vines climbing the hillsides toward higher altitudes that more closely parallel the ripening of the vines in Pirque. And the question becomes, are the wines of Alto Jahuel more closely associated with the Alto Maipo, or more in league with the rest of the Maipo Valley?
  Ignacio Recabarren has made wine in Alto Jahuel, Pirque and Santiago (Macul). "In Macul, you have a more extreme climate condition. When it's cold, it's cold. In a warm year like '99, Macul has the benefit of being a cooler area. Pirque is not as close to the Andes, and the Maipo River tempers the microclimate. In a good vintage, the differences are smaller." When asked to compare these regions to Alto Jahuel, he points out that "the grapes ripen earlier, especially in the flats. The grapes in the hills are closer to Pirque." Overall, he finds the conditions are warmer, so the acidity is lower. "I don't think Alto Jahuel is the same as Pirque, Puente Alto and Macul. But all these places produce very good red wines."
  Alvaro Espinoza has also made wine in both Alto Jahuel and Pirque, and agrees that the conditions are somewhat different. "Pirque is a little cooler; the grapes take longer to ripen and the wines have more minerality, more structure. In Alto Jahuel, the wines are riper, more concentrated and fruit-forward. The character may be different, but there is not much difference in terms of quality. Wines like [Santa Rita] Casa Real and [Carmen] Gold Reserve give the answer that it must be considered one of the most important regions of Maipo."
  History definitely argues for it, the 19th century Parque Santa Rita bracketing the south end of the Alto Maipo while Hacienda Macul brackets the north. And again, the parallel to the Haut-Médoc argues for inclusion: the commune of Margaux has sandier soils and a different character to its wines than St-Julien, Pauillac and St-Estèphe, where the vineyards are predominantly deep washes of river stones. In the end, the question becomes whether inclusion of all four zones is more valuable to wine drinkers, or more confusing. As a regular traveler to Chile since 1989, this writer would have a difficult time thinking of Alto Maipo without all four zones. For me, the wines do seem to belong in the same family, and it would seem to be the loss of one member of the family to cut off Alto Jahuel. Meanwhile, the process of defining Alto Maipo may lead to other divisions of the Maipo Valley - perhaps a Maipo River zone, or a Maipo Coast, emphasizing other significant distinctions in soil and climate.