The international connection between Detroit and Windsor, Ontario began in 1929.
The Ambassador Bridge construction was completed that year and officially opened Nov. 11, 1929. Just a year later, the Detroit-Windsor Tunnel construction was completed and dedicated Nov. 1, 1930.
Here is some history on the existing tunnel and bridge:
According to its website, www.dwtunnel.com, the tunnel was finished a year ahead of schedule in 1929. The tunnel is jointly owned by Detroit and Windsor. It is operated by two separate agreements by the Detroit and Canada Tunnel Corporation.
Approximately 27,000 to 29,000 vehicles pass through the Tunnel on a daily basis. The Tunnel handles almost nine million vehicles per year, of which 95 percent are cars and 5 percent are trucks, according to dwtunnel.com.
One and 1/2 million cubic feet of fresh air is pumped into the tunnel each minute.
A $50 Million renovation program was launched in 1993, including a completely new road surface, new sidewall tiling, new lighting, complete video surveillance and restoration of the Tunnel’s stone cover beneath the Detroit River, according to dwtunnel.com
Owned and operated by the Detroit International Bridge Company, along with the Canadian Transit Company, the Ambassador Bridge is the busiest international border crossing in North America.
Bridge construction began in 1927 and it was ready for use in 1929.
DIBC provides an extensive rundown of the Ambassador Bridge's history in this downloadable PDF: History of the Ambassador Bridge
Complete coverage: Detroit, Windsor bridge agreement