Type I collagen is the major fibrillar protein of connective tissues and is well known for its broad range of functions throughout the body. Individual triple helical collagen molecules undergo self-assembly to form higher-order structures including fibrils and networks. Since this process is strongly dependent on temperature, pH and ionic strength, it is believed that electrostatic, hydrophobic and entropic interactions are the main forces which direct fibril formation. Determining the mechanical behavior of collagen systems, from molecules in solution to a network of entangled chains, provides an understanding of the physical and chemical interactions between collagen chains that may contribute to fibril formation. To probe the micron-scale viscoelasticity of collagen solutions, we use optical tweezers and measure the local Brownian motion of an embedded probe particle. From high-bandwidth measurements (up to 100 kHz) of the particle's displacement, we obtain the local complex shear modulus of collagen solutions. In this study, we probe the concentration dependence of viscoelastic response and find that elasticity becomes comparable to viscous behavior at collagen concentrations of 5mg/ml. By varying electrostatic interactions in the system, we demonstrate the role they play in conferring elasticity to collagen solutions.