Interstate 25 in Colorado

In the US state of Colorado, Interstate 25 (I-25) is a big north–south highway. It goes through important cities like Colorado Springs, Denver, Fort Collins, Broomfield, Loveland, and Pueblo. The highway starts from the north near Carr and ends near Starkville.

I-25 is called different names along its path. In Denver, it is known as the Valley Highway. In Colorado Springs, it is called the Monument Valley Highway, and in Pueblo, it is named the Pueblo Freeway. Some parts of the road have special names, like the Ronald Reagan Highway in El Paso County and the John F. Kennedy Memorial Highway in Pueblo County.

The highway helps people travel and is part of the unofficial Pan-American Highway. It replaced older roads like US 87 and most of US 85 to make travel easier through the state.

Route description

Interstate 25 starts near the border with New Mexico and enters Colorado close to the Rocky Mountains. It goes through small towns and rural areas, heading north toward Pueblo. The road passes near lakes and parks, like Trinidad Lake and Pueblo Lake.

From Pueblo, the highway continues north, going close to Colorado Springs and Fort Carson. It passes important places such as Evergreen Cemetery and Colorado College. The road then enters Denver, winding around the city center and going near universities and parks.

After leaving Denver, Interstate 25 moves north through suburbs and farmland. It goes through cities like Thornton and Fort Collins, with Colorado State University nearby. The highway finally reaches the border with Wyoming after traveling through open countryside and small towns.

History

Construction

Ancestors and early freeways

Colorado started planning a modern road along the Front Range in 1944, before the national Interstate Highway system.

An old road called SH 1 was finished between Denver and Pueblo by 1919. It took about 2.5 hours to travel between Pueblo and Colorado Springs on this road, or 8.5 hours from Pueblo to Denver. This road was later improved and became US 85 and US 87 by 1930. It was now made of concrete and the trip between Pueblo and Colorado Springs was reduced to just one hour.

Denver (in 1948) and Pueblo (in 1949) were the first cities to start building multi-lane road sections along what would become I-25. Denver’s section was called the Valley Highway and was finished by 1958. Colorado Springs started building their Monument Valley Freeway in 1955, which was completed by July 1960. Pueblo’s part, the Pueblo Freeway, was done by July 1959.

Interstate completion

When the national Interstate Highway System began, connections started to be built. Wyoming built a link to Cheyenne in 1964, connecting to Colorado’s stretch.

Connecting to New Mexico was harder because the road had to go over Raton Pass, which is very high. Construction began in 1960, and a link to Trinidad was finished by 1963. The Trinidad Segment over Raton Pass was finally done in 1968.

The last part of I-25 in Colorado, connecting Walsenburg and Trinidad, was completed in 1969. Now, there were four lanes of fast, nonstop highway open for 305 miles from New Mexico to Wyoming.

Improvements and expansion

As more people and traffic grew in Colorado during the 1990s and 2000s, major improvements were planned for I-25.

T-REX (Denver)

The first big project was Transportation Expansion (T-REX). It widened nearly 17 miles of I-25 and the I-225 bypass around Denver. It also added new pedestrian and beauty improvements. T-REX also helped expand Denver’s public transportation lines.

The T-REX project began in early 2004 and finished in 2006. It cost $1.67 billion, which was less than planned and two years earlier than expected.

COSMIX (Colorado Springs)

Next was Colorado Springs Metro Interstate Expansion (COSMIX). The road through Colorado Springs had grown very busy. COSMIX started in 2005 and finished by the end of December 2007, four days early. It widened the road to three lanes in each direction and rebuilt two main intersections. It was planned to cost $225 million but finally cost $150 million.

COSMIX was the first part of a bigger plan for I-25 improvements. A second phase widened a 12-mile part to six lanes and added extra lanes at busy exits. The Air Force Academy exit was redesigned. This work was done by December 2014.

Greenland Wildlife Overpass

In 2025, the biggest wildlife overpass in North America was built over I-25 in Douglas County. It connects 39,000 acres of nature. The overpass is 200 feet wide and 209 feet long.

It is expected that the Greenland Wildlife Overpass will cut down wildlife-vehicle crashes by 90%.

Future

As of October 2020, a seven-mile part of Interstate 25 near Pueblo was improved. The upgrades made two bridges wider, added noise walls, made curves safer, and added lanes for slowing down or speeding up. This project cost $69 million and is now done.

There is talk about changing Interstate 25 in northern Colorado, from Broomfield to Fort Collins. Ideas include adding toll lanes or making the road wider. But there isn’t enough money or agreement on what to do. Traffic is growing fast in Weld and Larimer counties, so changes will need to happen soon.

In Colorado Springs, work is happening to extend Powers Boulevard to meet Interstate 25. This will make it easier to go around the north end of the town and connect Voyager Pkwy to the Interstate. The first phase included building a new interchange near exit 156, and it was finished in summer 2021.

The Gap is an 18-mile stretch of Interstate 25 between Castle Rock and Monument. It is the only part that has only four lanes between Denver and Colorado Springs. Because more people are living there and using the road, traffic has gotten busier. Efforts to improve this area are finished, and they cost $350 million from local and federal sources.

Exit list

Related routes

Auxiliary routes

Main article: Interstate 225

In Colorado, Interstate 25 has one special route called Interstate 225. This route is about 12 miles long and is near Denver. It starts from the main highway near the Denver Tech Center and ends at Interstate 70 north of Aurora. This route helps travelers avoid traffic in downtown Denver and gives a direct way to get to Denver International Airport from the southern suburbs. It is the only special route for Interstate 25, as there are no others in Wyoming or New Mexico.

Business routes

Main article: Business routes of Interstate 25

Interstate 25 has two special roads that connect small towns to the highway. In Aguilar, Business Spur 25 runs along Lynn Road, and in Walsenburg, Business Loop 25 serves the town. There used to be three more routes in Trinidad, Colorado Springs, and Castle Rock, but they are no longer in use.